b2sum: a new checksum utility with md5sum like interface

Note we don't support the --algorithm option of the
b2sum command in the external BLAKE2 project, as that
was deemed too confusing for users.
"BLAKE2b" was chosen as the default algorithm to use,
which is single threaded but performs well on 64 bit.

* src/blake2: CC0 source copied from external project.
* cfg.mk[VC_LIST_ALWAYS_EXCLUDE_REGEX]: Exclude blake2/
from syntax checks, make update-copyright, etc.
* src/local.mk: Reference the sources for b2sum,
and set the compilation flags.
* doc/coreutils.texi (b2sum invocation): Reference the
md5sum invocation node, and add descriptions of -l.
* tests/misc/b2sum.sh: Add new test.
* tests/local.mk: Reference new test.
* AUTHORS: Add new binary.
* README: Likewise.
* build-aux/gen-lists-of-programs.sh: Likewise.
* man/.gitignore: Likewise.
* scripts/git-hooks/commit-msg: Likewise.
* man/b2sum.x: New man page template.
* man/local.mk: Reference new template.
* src/.gitignore: Ignore new binaries.
* src/blake2/.gitignore: Ignore new build atrifacts.
* src/md5sum.c (usage): Describe the new -l option.
* NEWS: Mention the new program.

9 files changed, 1321 insertions, 14 deletions

diff --git a/src/.gitignore b/src/.gitignore
index c1f3b0d13..70ab2cac8 100644
--- a/src/.gitignore
+++ b/src/.gitignore
@@ -2,6 +2,7 @@
 /.dirstamp
 \[
 arch
+b2sum
 base32
 base64
 basename
diff --git a/src/blake2/.gitignore b/src/blake2/.gitignore
new file mode 100644
index 000000000..93d1552ba
--- /dev/null
+++ b/src/blake2/.gitignore
@@ -0,0 +1,2 @@
+/.dirstamp
+/.deps
diff --git a/src/blake2/b2sum.c b/src/blake2/b2sum.c
new file mode 100644
index 000000000..1c565e08c
--- /dev/null
+++ b/src/blake2/b2sum.c
@@ -0,0 +1,389 @@
+/*
+   BLAKE2 reference source code package - b2sum tool
+
+   Copyright 2012, Samuel Neves <sneves@dei.uc.pt>.  You may use this under the
+   terms of the CC0, the OpenSSL Licence, or the Apache Public License 2.0, at
+   your option.  The terms of these licenses can be found at:
+
+   - CC0 1.0 Universal : http://creativecommons.org/publicdomain/zero/1.0
+   - OpenSSL license   : https://www.openssl.org/source/license.html
+   - Apache 2.0        : http://www.apache.org/licenses/LICENSE-2.0
+
+   More information about the BLAKE2 hash function can be found at
+   https://blake2.net.
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+#include <errno.h>
+
+#include <ctype.h>
+#include <unistd.h>
+#include <getopt.h>
+#include <stdbool.h>
+
+#include "blake2.h"
+
+/* This will help compatibility with coreutils */
+int blake2b_stream( FILE *stream, void *resstream, size_t outbytes )
+{
+  int ret = -1;
+  size_t sum, n;
+  blake2b_state S[1];
+  static const size_t buffer_length = 32768;
+  uint8_t *buffer = ( uint8_t * )malloc( buffer_length );
+
+  if( !buffer ) return -1;
+
+  blake2b_init( S, outbytes );
+
+  while( 1 )
+  {
+    sum = 0;
+
+    while( 1 )
+    {
+      n = fread( buffer + sum, 1, buffer_length - sum, stream );
+      sum += n;
+
+      if( buffer_length == sum )
+        break;
+
+      if( 0 == n )
+      {
+        if( ferror( stream ) )
+          goto cleanup_buffer;
+
+        goto final_process;
+      }
+
+      if( feof( stream ) )
+        goto final_process;
+    }
+
+    blake2b_update( S, buffer, buffer_length );
+  }
+
+final_process:;
+
+  if( sum > 0 ) blake2b_update( S, buffer, sum );
+
+  blake2b_final( S, resstream, outbytes );
+  ret = 0;
+cleanup_buffer:
+  free( buffer );
+  return ret;
+}
+
+#if 0
+int blake2s_stream( FILE *stream, void *resstream, size_t outbytes )
+{
+  int ret = -1;
+  size_t sum, n;
+  blake2s_state S[1];
+  static const size_t buffer_length = 32768;
+  uint8_t *buffer = ( uint8_t * )malloc( buffer_length );
+
+  if( !buffer ) return -1;
+
+  blake2s_init( S, outbytes );
+
+  while( 1 )
+  {
+    sum = 0;
+
+    while( 1 )
+    {
+      n = fread( buffer + sum, 1, buffer_length - sum, stream );
+      sum += n;
+
+      if( buffer_length == sum )
+        break;
+
+      if( 0 == n )
+      {
+        if( ferror( stream ) )
+          goto cleanup_buffer;
+
+        goto final_process;
+      }
+
+      if( feof( stream ) )
+        goto final_process;
+    }
+
+    blake2s_update( S, buffer, buffer_length );
+  }
+
+final_process:;
+
+  if( sum > 0 ) blake2s_update( S, buffer, sum );
+
+  blake2s_final( S, resstream, outbytes );
+  ret = 0;
+cleanup_buffer:
+  free( buffer );
+  return ret;
+}
+
+
+int blake2sp_stream( FILE *stream, void *resstream, size_t outbytes )
+{
+  int ret = -1;
+  size_t sum, n;
+  blake2sp_state S[1];
+  static const size_t buffer_length = 16 * ( 1UL << 20 );
+  uint8_t *buffer = ( uint8_t * )malloc( buffer_length );
+
+  if( !buffer ) return -1;
+
+  blake2sp_init( S, outbytes );
+
+  while( 1 )
+  {
+    sum = 0;
+
+    while( 1 )
+    {
+      n = fread( buffer + sum, 1, buffer_length - sum, stream );
+      sum += n;
+
+      if( buffer_length == sum )
+        break;
+
+      if( 0 == n )
+      {
+        if( ferror( stream ) )
+          goto cleanup_buffer;
+
+        goto final_process;
+      }
+
+      if( feof( stream ) )
+        goto final_process;
+    }
+
+    blake2sp_update( S, buffer, buffer_length );
+  }
+
+final_process:;
+
+  if( sum > 0 ) blake2sp_update( S, buffer, sum );
+
+  blake2sp_final( S, resstream, outbytes );
+  ret = 0;
+cleanup_buffer:
+  free( buffer );
+  return ret;
+}
+
+
+int blake2bp_stream( FILE *stream, void *resstream, size_t outbytes )
+{
+  int ret = -1;
+  size_t sum, n;
+  blake2bp_state S[1];
+  static const size_t buffer_length = 16 * ( 1UL << 20 );
+  uint8_t *buffer = ( uint8_t * )malloc( buffer_length );
+
+  if( !buffer ) return -1;
+
+  blake2bp_init( S, outbytes );
+
+  while( 1 )
+  {
+    sum = 0;
+
+    while( 1 )
+    {
+      n = fread( buffer + sum, 1, buffer_length - sum, stream );
+      sum += n;
+
+      if( buffer_length == sum )
+        break;
+
+      if( 0 == n )
+      {
+        if( ferror( stream ) )
+          goto cleanup_buffer;
+
+        goto final_process;
+      }
+
+      if( feof( stream ) )
+        goto final_process;
+    }
+
+    blake2bp_update( S, buffer, buffer_length );
+  }
+
+final_process:;
+
+  if( sum > 0 ) blake2bp_update( S, buffer, sum );
+
+  blake2bp_final( S, resstream, outbytes );
+  ret = 0;
+cleanup_buffer:
+  free( buffer );
+  return ret;
+}
+
+typedef int ( *blake2fn )( FILE *, void *, size_t );
+
+
+static void usage( char **argv, int errcode )
+{
+  FILE *out = errcode ? stderr : stdout;
+  fprintf( out, "Usage: %s [OPTION]... [FILE]...\n", argv[0] );
+  fprintf( out, "\n" );
+  fprintf( out, "With no FILE, or when FILE is -, read standard input.\n" );
+  fprintf( out, "\n" );
+  fprintf( out, "  -a <algo>    hash algorithm (blake2b is default): \n"
+                "               [blake2b|blake2s|blake2bp|blake2sp]\n" );
+  fprintf( out, "  -l <length>  digest length in bits, must not exceed the maximum for\n"
+                "               the selected algorithm and must be a multiple of 8\n" );
+  fprintf( out, "  --tag        create a BSD-style checksum\n" );
+  fprintf( out, "  --help       display this help and exit\n" );
+  exit( errcode );
+}
+
+int main( int argc, char **argv )
+{
+  blake2fn blake2_stream = blake2b_stream;
+  unsigned long maxbytes = BLAKE2B_OUTBYTES;
+  const char *algorithm = "BLAKE2b";
+  unsigned long outbytes = 0;
+  unsigned char hash[BLAKE2B_OUTBYTES] = {0};
+  bool bsdstyle = false;
+  int c, i;
+  opterr = 1;
+
+  while( 1 )
+  {
+    int option_index = 0;
+    char *end = NULL;
+    unsigned long outbits;
+    static struct option long_options[] = {
+      { "help",  no_argument, 0,  0  },
+      { "tag",   no_argument, 0,  0  },
+      { NULL, 0, NULL, 0 }
+    };
+
+    c = getopt_long( argc, argv, "a:l:", long_options, &option_index );
+    if( c == -1 ) break;
+    switch( c )
+    {
+    case 'a':
+      if( 0 == strcmp( optarg, "blake2b" ) )
+      {
+        blake2_stream = blake2b_stream;
+        maxbytes = BLAKE2B_OUTBYTES;
+        algorithm = "BLAKE2b";
+      }
+      else if ( 0 == strcmp( optarg, "blake2s" ) )
+      {
+        blake2_stream = blake2s_stream;
+        maxbytes = BLAKE2S_OUTBYTES;
+        algorithm = "BLAKE2s";
+      }
+      else if ( 0 == strcmp( optarg, "blake2bp" ) )
+      {
+        blake2_stream = blake2bp_stream;
+        maxbytes = BLAKE2B_OUTBYTES;
+        algorithm = "BLAKE2bp";
+      }
+      else if ( 0 == strcmp( optarg, "blake2sp" ) )
+      {
+        blake2_stream = blake2sp_stream;
+        maxbytes = BLAKE2S_OUTBYTES;
+        algorithm = "BLAKE2sp";
+      }
+      else
+      {
+        printf( "Invalid function name: `%s'\n", optarg );
+        usage( argv, 111 );
+      }
+
+      break;
+
+    case 'l':
+      outbits = strtoul(optarg, &end, 10);
+      if( !end || *end != '\0' || outbits % 8 != 0)
+      {
+        printf( "Invalid length argument: `%s'\n", optarg);
+        usage( argv, 111 );
+      }
+      outbytes = outbits / 8;
+      break;
+
+    case 0:
+      if( 0 == strcmp( "help", long_options[option_index].name ) )
+        usage( argv, 0 );
+      else if( 0 == strcmp( "tag", long_options[option_index].name ) )
+        bsdstyle = true;
+      break;
+
+    case '?':
+      usage( argv, 1 );
+      break;
+    }
+  }
+
+  if(outbytes > maxbytes)
+  {
+    printf( "Invalid length argument: %lu\n", outbytes * 8 );
+    printf( "Maximum digest length for %s is %lu\n", algorithm, maxbytes * 8 );
+    usage( argv, 111 );
+  }
+  else if( outbytes == 0 )
+    outbytes = maxbytes;
+
+  if( optind == argc )
+    argv[argc++] = (char *) "-";
+
+  for( i = optind; i < argc; ++i )
+  {
+    FILE *f = NULL;
+    if( argv[i][0] == '-' && argv[i][1] == '\0' )
+      f = stdin;
+    else
+      f = fopen( argv[i], "rb" );
+
+    if( !f )
+    {
+      fprintf( stderr, "Could not open `%s': %s\n", argv[i], strerror( errno ) );
+      continue;
+    }
+
+    if( blake2_stream( f, hash, outbytes ) < 0 )
+    {
+      fprintf( stderr, "Failed to hash `%s'\n", argv[i] );
+    }
+    else
+    {
+      size_t j;
+      if( bsdstyle )
+      {
+        if( outbytes < maxbytes )
+          printf( "%s-%lu (%s) = ", algorithm, outbytes * 8, argv[i] );
+        else
+          printf( "%s (%s) = ", algorithm, argv[i] );
+      }
+
+      for( j = 0; j < outbytes; ++j )
+        printf( "%02x", hash[j] );
+
+      if( bsdstyle )
+        printf( "\n" );
+      else
+        printf( "  %s\n", argv[i] );
+    }
+
+    if( f != stdin ) fclose( f );
+  }
+
+  return 0;
+}
+#endif
diff --git a/src/blake2/b2sum.h b/src/blake2/b2sum.h
new file mode 100644
index 000000000..59120f6e8
--- /dev/null
+++ b/src/blake2/b2sum.h
@@ -0,0 +1,19 @@
+/*
+   BLAKE2 reference source code package - b2sum tool
+
+   Copyright 2012, Samuel Neves <sneves@dei.uc.pt>.  You may use this under the
+   terms of the CC0, the OpenSSL Licence, or the Apache Public License 2.0, at
+   your option.  The terms of these licenses can be found at:
+
+   - CC0 1.0 Universal : http://creativecommons.org/publicdomain/zero/1.0
+   - OpenSSL license   : https://www.openssl.org/source/license.html
+   - Apache 2.0        : http://www.apache.org/licenses/LICENSE-2.0
+
+   More information about the BLAKE2 hash function can be found at
+   https://blake2.net.
+*/
+
+int blake2b_stream( FILE *stream, void *resstream, size_t outbytes );
+typedef int ( *blake2fn )( FILE *, void *, size_t );
+#define BLAKE2S_OUTBYTES 32
+#define BLAKE2B_OUTBYTES 64
diff --git a/src/blake2/blake2-impl.h b/src/blake2/blake2-impl.h
new file mode 100644
index 000000000..5dff7fc7a
--- /dev/null
+++ b/src/blake2/blake2-impl.h
@@ -0,0 +1,160 @@
+/*
+   BLAKE2 reference source code package - reference C implementations
+
+   Copyright 2012, Samuel Neves <sneves@dei.uc.pt>.  You may use this under the
+   terms of the CC0, the OpenSSL Licence, or the Apache Public License 2.0, at
+   your option.  The terms of these licenses can be found at:
+
+   - CC0 1.0 Universal : http://creativecommons.org/publicdomain/zero/1.0
+   - OpenSSL license   : https://www.openssl.org/source/license.html
+   - Apache 2.0        : http://www.apache.org/licenses/LICENSE-2.0
+
+   More information about the BLAKE2 hash function can be found at
+   https://blake2.net.
+*/
+#ifndef BLAKE2_IMPL_H
+#define BLAKE2_IMPL_H
+
+#include <stdint.h>
+#include <string.h>
+
+#if !defined(__cplusplus) && (!defined(__STDC_VERSION__) || __STDC_VERSION__ < 199901L)
+  #if   defined(_MSC_VER)
+    #define BLAKE2_INLINE __inline
+  #elif defined(__GNUC__)
+    #define BLAKE2_INLINE __inline__
+  #else
+    #define BLAKE2_INLINE
+  #endif
+#else
+  #define BLAKE2_INLINE inline
+#endif
+
+static BLAKE2_INLINE uint32_t load32( const void *src )
+{
+#if defined(NATIVE_LITTLE_ENDIAN)
+  uint32_t w;
+  memcpy(&w, src, sizeof w);
+  return w;
+#else
+  const uint8_t *p = ( const uint8_t * )src;
+  return (( uint32_t )( p[0] ) <<  0) |
+         (( uint32_t )( p[1] ) <<  8) |
+         (( uint32_t )( p[2] ) << 16) |
+         (( uint32_t )( p[3] ) << 24) ;
+#endif
+}
+
+static BLAKE2_INLINE uint64_t load64( const void *src )
+{
+#if defined(NATIVE_LITTLE_ENDIAN)
+  uint64_t w;
+  memcpy(&w, src, sizeof w);
+  return w;
+#else
+  const uint8_t *p = ( const uint8_t * )src;
+  return (( uint64_t )( p[0] ) <<  0) |
+         (( uint64_t )( p[1] ) <<  8) |
+         (( uint64_t )( p[2] ) << 16) |
+         (( uint64_t )( p[3] ) << 24) |
+         (( uint64_t )( p[4] ) << 32) |
+         (( uint64_t )( p[5] ) << 40) |
+         (( uint64_t )( p[6] ) << 48) |
+         (( uint64_t )( p[7] ) << 56) ;
+#endif
+}
+
+static BLAKE2_INLINE uint16_t load16( const void *src )
+{
+#if defined(NATIVE_LITTLE_ENDIAN)
+  uint16_t w;
+  memcpy(&w, src, sizeof w);
+  return w;
+#else
+  const uint8_t *p = ( const uint8_t * )src;
+  return (( uint16_t )( p[0] ) <<  0) |
+         (( uint16_t )( p[1] ) <<  8) ;
+#endif
+}
+
+static BLAKE2_INLINE void store16( void *dst, uint16_t w )
+{
+#if defined(NATIVE_LITTLE_ENDIAN)
+  memcpy(dst, &w, sizeof w);
+#else
+  uint8_t *p = ( uint8_t * )dst;
+  *p++ = ( uint8_t )w; w >>= 8;
+  *p++ = ( uint8_t )w;
+#endif
+}
+
+static BLAKE2_INLINE void store32( void *dst, uint32_t w )
+{
+#if defined(NATIVE_LITTLE_ENDIAN)
+  memcpy(dst, &w, sizeof w);
+#else
+  uint8_t *p = ( uint8_t * )dst;
+  p[0] = (uint8_t)(w >>  0);
+  p[1] = (uint8_t)(w >>  8);
+  p[2] = (uint8_t)(w >> 16);
+  p[3] = (uint8_t)(w >> 24);
+#endif
+}
+
+static BLAKE2_INLINE void store64( void *dst, uint64_t w )
+{
+#if defined(NATIVE_LITTLE_ENDIAN)
+  memcpy(dst, &w, sizeof w);
+#else
+  uint8_t *p = ( uint8_t * )dst;
+  p[0] = (uint8_t)(w >>  0);
+  p[1] = (uint8_t)(w >>  8);
+  p[2] = (uint8_t)(w >> 16);
+  p[3] = (uint8_t)(w >> 24);
+  p[4] = (uint8_t)(w >> 32);
+  p[5] = (uint8_t)(w >> 40);
+  p[6] = (uint8_t)(w >> 48);
+  p[7] = (uint8_t)(w >> 56);
+#endif
+}
+
+static BLAKE2_INLINE uint64_t load48( const void *src )
+{
+  const uint8_t *p = ( const uint8_t * )src;
+  return (( uint64_t )( p[0] ) <<  0) |
+         (( uint64_t )( p[1] ) <<  8) |
+         (( uint64_t )( p[2] ) << 16) |
+         (( uint64_t )( p[3] ) << 24) |
+         (( uint64_t )( p[4] ) << 32) |
+         (( uint64_t )( p[5] ) << 40) ;
+}
+
+static BLAKE2_INLINE void store48( void *dst, uint64_t w )
+{
+  uint8_t *p = ( uint8_t * )dst;
+  p[0] = (uint8_t)(w >>  0);
+  p[1] = (uint8_t)(w >>  8);
+  p[2] = (uint8_t)(w >> 16);
+  p[3] = (uint8_t)(w >> 24);
+  p[4] = (uint8_t)(w >> 32);
+  p[5] = (uint8_t)(w >> 40);
+}
+
+static BLAKE2_INLINE uint32_t rotr32( const uint32_t w, const unsigned c )
+{
+  return ( w >> c ) | ( w << ( 32 - c ) );
+}
+
+static BLAKE2_INLINE uint64_t rotr64( const uint64_t w, const unsigned c )
+{
+  return ( w >> c ) | ( w << ( 64 - c ) );
+}
+
+/* prevents compiler optimizing out memset() */
+static BLAKE2_INLINE void secure_zero_memory(void *v, size_t n)
+{
+  static void *(*const volatile memset_v)(void *, int, size_t) = &memset;
+  memset_v(v, 0, n);
+}
+
+#endif
diff --git a/src/blake2/blake2.h b/src/blake2/blake2.h
new file mode 100644
index 000000000..ad62f260e
--- /dev/null
+++ b/src/blake2/blake2.h
@@ -0,0 +1,195 @@
+/*
+   BLAKE2 reference source code package - reference C implementations
+
+   Copyright 2012, Samuel Neves <sneves@dei.uc.pt>.  You may use this under the
+   terms of the CC0, the OpenSSL Licence, or the Apache Public License 2.0, at
+   your option.  The terms of these licenses can be found at:
+
+   - CC0 1.0 Universal : http://creativecommons.org/publicdomain/zero/1.0
+   - OpenSSL license   : https://www.openssl.org/source/license.html
+   - Apache 2.0        : http://www.apache.org/licenses/LICENSE-2.0
+
+   More information about the BLAKE2 hash function can be found at
+   https://blake2.net.
+*/
+#ifndef BLAKE2_H
+#define BLAKE2_H
+
+#include <stddef.h>
+#include <stdint.h>
+
+#if defined(_MSC_VER)
+#define BLAKE2_PACKED(x) __pragma(pack(push, 1)) x __pragma(pack(pop))
+#else
+#define BLAKE2_PACKED(x) x __attribute__((packed))
+#endif
+
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
+  enum blake2s_constant
+  {
+    BLAKE2S_BLOCKBYTES = 64,
+    BLAKE2S_OUTBYTES   = 32,
+    BLAKE2S_KEYBYTES   = 32,
+    BLAKE2S_SALTBYTES  = 8,
+    BLAKE2S_PERSONALBYTES = 8
+  };
+
+  enum blake2b_constant
+  {
+    BLAKE2B_BLOCKBYTES = 128,
+    BLAKE2B_OUTBYTES   = 64,
+    BLAKE2B_KEYBYTES   = 64,
+    BLAKE2B_SALTBYTES  = 16,
+    BLAKE2B_PERSONALBYTES = 16
+  };
+
+  typedef struct blake2s_state__
+  {
+    uint32_t h[8];
+    uint32_t t[2];
+    uint32_t f[2];
+    uint8_t  buf[BLAKE2S_BLOCKBYTES];
+    size_t   buflen;
+    size_t   outlen;
+    uint8_t  last_node;
+  } blake2s_state;
+
+  typedef struct blake2b_state__
+  {
+    uint64_t h[8];
+    uint64_t t[2];
+    uint64_t f[2];
+    uint8_t  buf[BLAKE2B_BLOCKBYTES];
+    size_t   buflen;
+    size_t   outlen;
+    uint8_t  last_node;
+  } blake2b_state;
+
+  typedef struct blake2sp_state__
+  {
+    blake2s_state S[8][1];
+    blake2s_state R[1];
+    uint8_t       buf[8 * BLAKE2S_BLOCKBYTES];
+    size_t        buflen;
+    size_t        outlen;
+  } blake2sp_state;
+
+  typedef struct blake2bp_state__
+  {
+    blake2b_state S[4][1];
+    blake2b_state R[1];
+    uint8_t       buf[4 * BLAKE2B_BLOCKBYTES];
+    size_t        buflen;
+    size_t        outlen;
+  } blake2bp_state;
+
+
+  BLAKE2_PACKED(struct blake2s_param__
+  {
+    uint8_t  digest_length; /* 1 */
+    uint8_t  key_length;    /* 2 */
+    uint8_t  fanout;        /* 3 */
+    uint8_t  depth;         /* 4 */
+    uint32_t leaf_length;   /* 8 */
+    uint32_t node_offset;  /* 12 */
+    uint16_t xof_length;    /* 14 */
+    uint8_t  node_depth;    /* 15 */
+    uint8_t  inner_length;  /* 16 */
+    /* uint8_t  reserved[0]; */
+    uint8_t  salt[BLAKE2S_SALTBYTES]; /* 24 */
+    uint8_t  personal[BLAKE2S_PERSONALBYTES];  /* 32 */
+  });
+
+  typedef struct blake2s_param__ blake2s_param;
+
+  BLAKE2_PACKED(struct blake2b_param__
+  {
+    uint8_t  digest_length; /* 1 */
+    uint8_t  key_length;    /* 2 */
+    uint8_t  fanout;        /* 3 */
+    uint8_t  depth;         /* 4 */
+    uint32_t leaf_length;   /* 8 */
+    uint32_t node_offset;   /* 12 */
+    uint32_t xof_length;    /* 16 */
+    uint8_t  node_depth;    /* 17 */
+    uint8_t  inner_length;  /* 18 */
+    uint8_t  reserved[14];  /* 32 */
+    uint8_t  salt[BLAKE2B_SALTBYTES]; /* 48 */
+    uint8_t  personal[BLAKE2B_PERSONALBYTES];  /* 64 */
+  });
+
+  typedef struct blake2b_param__ blake2b_param;
+
+  typedef struct blake2xs_state__
+  {
+    blake2s_state S[1];
+    blake2s_param P[1];
+  } blake2xs_state;
+
+  typedef struct blake2xb_state__
+  {
+    blake2b_state S[1];
+    blake2b_param P[1];
+  } blake2xb_state;
+
+  /* Padded structs result in a compile-time error */
+  enum {
+    BLAKE2_DUMMY_1 = 1/(sizeof(blake2s_param) == BLAKE2S_OUTBYTES),
+    BLAKE2_DUMMY_2 = 1/(sizeof(blake2b_param) == BLAKE2B_OUTBYTES)
+  };
+
+  /* Streaming API */
+  int blake2s_init( blake2s_state *S, size_t outlen );
+  int blake2s_init_key( blake2s_state *S, size_t outlen, const void *key, size_t keylen );
+  int blake2s_init_param( blake2s_state *S, const blake2s_param *P );
+  int blake2s_update( blake2s_state *S, const void *in, size_t inlen );
+  int blake2s_final( blake2s_state *S, void *out, size_t outlen );
+
+  int blake2b_init( blake2b_state *S, size_t outlen );
+  int blake2b_init_key( blake2b_state *S, size_t outlen, const void *key, size_t keylen );
+  int blake2b_init_param( blake2b_state *S, const blake2b_param *P );
+  int blake2b_update( blake2b_state *S, const void *in, size_t inlen );
+  int blake2b_final( blake2b_state *S, void *out, size_t outlen );
+
+  int blake2sp_init( blake2sp_state *S, size_t outlen );
+  int blake2sp_init_key( blake2sp_state *S, size_t outlen, const void *key, size_t keylen );
+  int blake2sp_update( blake2sp_state *S, const void *in, size_t inlen );
+  int blake2sp_final( blake2sp_state *S, void *out, size_t outlen );
+
+  int blake2bp_init( blake2bp_state *S, size_t outlen );
+  int blake2bp_init_key( blake2bp_state *S, size_t outlen, const void *key, size_t keylen );
+  int blake2bp_update( blake2bp_state *S, const void *in, size_t inlen );
+  int blake2bp_final( blake2bp_state *S, void *out, size_t outlen );
+
+  /* Variable output length API */
+  int blake2xs_init( blake2xs_state *S, const size_t outlen );
+  int blake2xs_init_key( blake2xs_state *S, const size_t outlen, const void *key, size_t keylen );
+  int blake2xs_update( blake2xs_state *S, const void *in, size_t inlen );
+  int blake2xs_final(blake2xs_state *S, void *out, size_t outlen);
+
+  int blake2xb_init( blake2xb_state *S, const size_t outlen );
+  int blake2xb_init_key( blake2xb_state *S, const size_t outlen, const void *key, size_t keylen );
+  int blake2xb_update( blake2xb_state *S, const void *in, size_t inlen );
+  int blake2xb_final(blake2xb_state *S, void *out, size_t outlen);
+
+  /* Simple API */
+  int blake2s( void *out, size_t outlen, const void *in, size_t inlen, const void *key, size_t keylen );
+  int blake2b( void *out, size_t outlen, const void *in, size_t inlen, const void *key, size_t keylen );
+
+  int blake2sp( void *out, size_t outlen, const void *in, size_t inlen, const void *key, size_t keylen );
+  int blake2bp( void *out, size_t outlen, const void *in, size_t inlen, const void *key, size_t keylen );
+
+  int blake2xs( void *out, size_t outlen, const void *in, size_t inlen, const void *key, size_t keylen );
+  int blake2xb( void *out, size_t outlen, const void *in, size_t inlen, const void *key, size_t keylen );
+
+  /* This is simply an alias for blake2b */
+  int blake2( void *out, size_t outlen, const void *in, size_t inlen, const void *key, size_t keylen );
+
+#if defined(__cplusplus)
+}
+#endif
+
+#endif
diff --git a/src/blake2/blake2b-ref.c b/src/blake2/blake2b-ref.c
new file mode 100644
index 000000000..cd38b1ba0
--- /dev/null
+++ b/src/blake2/blake2b-ref.c
@@ -0,0 +1,379 @@
+/*
+   BLAKE2 reference source code package - reference C implementations
+
+   Copyright 2012, Samuel Neves <sneves@dei.uc.pt>.  You may use this under the
+   terms of the CC0, the OpenSSL Licence, or the Apache Public License 2.0, at
+   your option.  The terms of these licenses can be found at:
+
+   - CC0 1.0 Universal : http://creativecommons.org/publicdomain/zero/1.0
+   - OpenSSL license   : https://www.openssl.org/source/license.html
+   - Apache 2.0        : http://www.apache.org/licenses/LICENSE-2.0
+
+   More information about the BLAKE2 hash function can be found at
+   https://blake2.net.
+*/
+
+#include <stdint.h>
+#include <string.h>
+#include <stdio.h>
+
+#include "blake2.h"
+#include "blake2-impl.h"
+
+static const uint64_t blake2b_IV[8] =
+{
+  0x6a09e667f3bcc908ULL, 0xbb67ae8584caa73bULL,
+  0x3c6ef372fe94f82bULL, 0xa54ff53a5f1d36f1ULL,
+  0x510e527fade682d1ULL, 0x9b05688c2b3e6c1fULL,
+  0x1f83d9abfb41bd6bULL, 0x5be0cd19137e2179ULL
+};
+
+static const uint8_t blake2b_sigma[12][16] =
+{
+  {  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15 } ,
+  { 14, 10,  4,  8,  9, 15, 13,  6,  1, 12,  0,  2, 11,  7,  5,  3 } ,
+  { 11,  8, 12,  0,  5,  2, 15, 13, 10, 14,  3,  6,  7,  1,  9,  4 } ,
+  {  7,  9,  3,  1, 13, 12, 11, 14,  2,  6,  5, 10,  4,  0, 15,  8 } ,
+  {  9,  0,  5,  7,  2,  4, 10, 15, 14,  1, 11, 12,  6,  8,  3, 13 } ,
+  {  2, 12,  6, 10,  0, 11,  8,  3,  4, 13,  7,  5, 15, 14,  1,  9 } ,
+  { 12,  5,  1, 15, 14, 13,  4, 10,  0,  7,  6,  3,  9,  2,  8, 11 } ,
+  { 13, 11,  7, 14, 12,  1,  3,  9,  5,  0, 15,  4,  8,  6,  2, 10 } ,
+  {  6, 15, 14,  9, 11,  3,  0,  8, 12,  2, 13,  7,  1,  4, 10,  5 } ,
+  { 10,  2,  8,  4,  7,  6,  1,  5, 15, 11,  9, 14,  3, 12, 13 , 0 } ,
+  {  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14, 15 } ,
+  { 14, 10,  4,  8,  9, 15, 13,  6,  1, 12,  0,  2, 11,  7,  5,  3 }
+};
+
+
+static void blake2b_set_lastnode( blake2b_state *S )
+{
+  S->f[1] = (uint64_t)-1;
+}
+
+/* Some helper functions, not necessarily useful */
+static int blake2b_is_lastblock( const blake2b_state *S )
+{
+  return S->f[0] != 0;
+}
+
+static void blake2b_set_lastblock( blake2b_state *S )
+{
+  if( S->last_node ) blake2b_set_lastnode( S );
+
+  S->f[0] = (uint64_t)-1;
+}
+
+static void blake2b_increment_counter( blake2b_state *S, const uint64_t inc )
+{
+  S->t[0] += inc;
+  S->t[1] += ( S->t[0] < inc );
+}
+
+static void blake2b_init0( blake2b_state *S )
+{
+  size_t i;
+  memset( S, 0, sizeof( blake2b_state ) );
+
+  for( i = 0; i < 8; ++i ) S->h[i] = blake2b_IV[i];
+}
+
+/* init xors IV with input parameter block */
+int blake2b_init_param( blake2b_state *S, const blake2b_param *P )
+{
+  const uint8_t *p = ( const uint8_t * )( P );
+  size_t i;
+
+  blake2b_init0( S );
+
+  /* IV XOR ParamBlock */
+  for( i = 0; i < 8; ++i )
+    S->h[i] ^= load64( p + sizeof( S->h[i] ) * i );
+
+  S->outlen = P->digest_length;
+  return 0;
+}
+
+
+
+int blake2b_init( blake2b_state *S, size_t outlen )
+{
+  blake2b_param P[1];
+
+  if ( ( !outlen ) || ( outlen > BLAKE2B_OUTBYTES ) ) return -1;
+
+  P->digest_length = (uint8_t)outlen;
+  P->key_length    = 0;
+  P->fanout        = 1;
+  P->depth         = 1;
+  store32( &P->leaf_length, 0 );
+  store32( &P->node_offset, 0 );
+  store32( &P->xof_length, 0 );
+  P->node_depth    = 0;
+  P->inner_length  = 0;
+  memset( P->reserved, 0, sizeof( P->reserved ) );
+  memset( P->salt,     0, sizeof( P->salt ) );
+  memset( P->personal, 0, sizeof( P->personal ) );
+  return blake2b_init_param( S, P );
+}
+
+
+int blake2b_init_key( blake2b_state *S, size_t outlen, const void *key, size_t keylen )
+{
+  blake2b_param P[1];
+
+  if ( ( !outlen ) || ( outlen > BLAKE2B_OUTBYTES ) ) return -1;
+
+  if ( !key || !keylen || keylen > BLAKE2B_KEYBYTES ) return -1;
+
+  P->digest_length = (uint8_t)outlen;
+  P->key_length    = (uint8_t)keylen;
+  P->fanout        = 1;
+  P->depth         = 1;
+  store32( &P->leaf_length, 0 );
+  store32( &P->node_offset, 0 );
+  store32( &P->xof_length, 0 );
+  P->node_depth    = 0;
+  P->inner_length  = 0;
+  memset( P->reserved, 0, sizeof( P->reserved ) );
+  memset( P->salt,     0, sizeof( P->salt ) );
+  memset( P->personal, 0, sizeof( P->personal ) );
+
+  if( blake2b_init_param( S, P ) < 0 ) return -1;
+
+  {
+    uint8_t block[BLAKE2B_BLOCKBYTES];
+    memset( block, 0, BLAKE2B_BLOCKBYTES );
+    memcpy( block, key, keylen );
+    blake2b_update( S, block, BLAKE2B_BLOCKBYTES );
+    secure_zero_memory( block, BLAKE2B_BLOCKBYTES ); /* Burn the key from stack */
+  }
+  return 0;
+}
+
+#define G(r,i,a,b,c,d)                      \
+  do {                                      \
+    a = a + b + m[blake2b_sigma[r][2*i+0]]; \
+    d = rotr64(d ^ a, 32);                  \
+    c = c + d;                              \
+    b = rotr64(b ^ c, 24);                  \
+    a = a + b + m[blake2b_sigma[r][2*i+1]]; \
+    d = rotr64(d ^ a, 16);                  \
+    c = c + d;                              \
+    b = rotr64(b ^ c, 63);                  \
+  } while(0)
+
+#define ROUND(r)                    \
+  do {                              \
+    G(r,0,v[ 0],v[ 4],v[ 8],v[12]); \
+    G(r,1,v[ 1],v[ 5],v[ 9],v[13]); \
+    G(r,2,v[ 2],v[ 6],v[10],v[14]); \
+    G(r,3,v[ 3],v[ 7],v[11],v[15]); \
+    G(r,4,v[ 0],v[ 5],v[10],v[15]); \
+    G(r,5,v[ 1],v[ 6],v[11],v[12]); \
+    G(r,6,v[ 2],v[ 7],v[ 8],v[13]); \
+    G(r,7,v[ 3],v[ 4],v[ 9],v[14]); \
+  } while(0)
+
+static void blake2b_compress( blake2b_state *S, const uint8_t block[BLAKE2B_BLOCKBYTES] )
+{
+  uint64_t m[16];
+  uint64_t v[16];
+  size_t i;
+
+  for( i = 0; i < 16; ++i ) {
+    m[i] = load64( block + i * sizeof( m[i] ) );
+  }
+
+  for( i = 0; i < 8; ++i ) {
+    v[i] = S->h[i];
+  }
+
+  v[ 8] = blake2b_IV[0];
+  v[ 9] = blake2b_IV[1];
+  v[10] = blake2b_IV[2];
+  v[11] = blake2b_IV[3];
+  v[12] = blake2b_IV[4] ^ S->t[0];
+  v[13] = blake2b_IV[5] ^ S->t[1];
+  v[14] = blake2b_IV[6] ^ S->f[0];
+  v[15] = blake2b_IV[7] ^ S->f[1];
+
+  ROUND( 0 );
+  ROUND( 1 );
+  ROUND( 2 );
+  ROUND( 3 );
+  ROUND( 4 );
+  ROUND( 5 );
+  ROUND( 6 );
+  ROUND( 7 );
+  ROUND( 8 );
+  ROUND( 9 );
+  ROUND( 10 );
+  ROUND( 11 );
+
+  for( i = 0; i < 8; ++i ) {
+    S->h[i] = S->h[i] ^ v[i] ^ v[i + 8];
+  }
+}
+
+#undef G
+#undef ROUND
+
+int blake2b_update( blake2b_state *S, const void *pin, size_t inlen )
+{
+  const unsigned char * in = (const unsigned char *)pin;
+  if( inlen > 0 )
+  {
+    size_t left = S->buflen;
+    size_t fill = BLAKE2B_BLOCKBYTES - left;
+    if( inlen > fill )
+    {
+      S->buflen = 0;
+      memcpy( S->buf + left, in, fill ); /* Fill buffer */
+      blake2b_increment_counter( S, BLAKE2B_BLOCKBYTES );
+      blake2b_compress( S, S->buf ); /* Compress */
+      in += fill; inlen -= fill;
+      while(inlen > BLAKE2B_BLOCKBYTES) {
+        blake2b_increment_counter(S, BLAKE2B_BLOCKBYTES);
+        blake2b_compress( S, in );
+        in += BLAKE2B_BLOCKBYTES;
+        inlen -= BLAKE2B_BLOCKBYTES;
+      }
+    }
+    memcpy( S->buf + S->buflen, in, inlen );
+    S->buflen += inlen;
+  }
+  return 0;
+}
+
+int blake2b_final( blake2b_state *S, void *out, size_t outlen )
+{
+  uint8_t buffer[BLAKE2B_OUTBYTES] = {0};
+  size_t i;
+
+  if( out == NULL || outlen < S->outlen )
+    return -1;
+
+  if( blake2b_is_lastblock( S ) )
+    return -1;
+
+  blake2b_increment_counter( S, S->buflen );
+  blake2b_set_lastblock( S );
+  memset( S->buf + S->buflen, 0, BLAKE2B_BLOCKBYTES - S->buflen ); /* Padding */
+  blake2b_compress( S, S->buf );
+
+  for( i = 0; i < 8; ++i ) /* Output full hash to temp buffer */
+    store64( buffer + sizeof( S->h[i] ) * i, S->h[i] );
+
+  memcpy( out, buffer, S->outlen );
+  secure_zero_memory(buffer, sizeof(buffer));
+  return 0;
+}
+
+/* inlen, at least, should be uint64_t. Others can be size_t. */
+int blake2b( void *out, size_t outlen, const void *in, size_t inlen, const void *key, size_t keylen )
+{
+  blake2b_state S[1];
+
+  /* Verify parameters */
+  if ( NULL == in && inlen > 0 ) return -1;
+
+  if ( NULL == out ) return -1;
+
+  if( NULL == key && keylen > 0 ) return -1;
+
+  if( !outlen || outlen > BLAKE2B_OUTBYTES ) return -1;
+
+  if( keylen > BLAKE2B_KEYBYTES ) return -1;
+
+  if( keylen > 0 )
+  {
+    if( blake2b_init_key( S, outlen, key, keylen ) < 0 ) return -1;
+  }
+  else
+  {
+    if( blake2b_init( S, outlen ) < 0 ) return -1;
+  }
+
+  blake2b_update( S, ( const uint8_t * )in, inlen );
+  blake2b_final( S, out, outlen );
+  return 0;
+}
+
+int blake2( void *out, size_t outlen, const void *in, size_t inlen, const void *key, size_t keylen ) {
+  return blake2b(out, outlen, in, inlen, key, keylen);
+}
+
+#if defined(SUPERCOP)
+int crypto_hash( unsigned char *out, unsigned char *in, unsigned long long inlen )
+{
+  return blake2b( out, BLAKE2B_OUTBYTES, in, inlen, NULL, 0 );
+}
+#endif
+
+#if defined(BLAKE2B_SELFTEST)
+#include <string.h>
+#include "blake2-kat.h"
+int main( void )
+{
+  uint8_t key[BLAKE2B_KEYBYTES];
+  uint8_t buf[BLAKE2_KAT_LENGTH];
+  size_t i, step;
+
+  for( i = 0; i < BLAKE2B_KEYBYTES; ++i )
+    key[i] = ( uint8_t )i;
+
+  for( i = 0; i < BLAKE2_KAT_LENGTH; ++i )
+    buf[i] = ( uint8_t )i;
+
+  /* Test simple API */
+  for( i = 0; i < BLAKE2_KAT_LENGTH; ++i )
+  {
+    uint8_t hash[BLAKE2B_OUTBYTES];
+    blake2b( hash, BLAKE2B_OUTBYTES, buf, i, key, BLAKE2B_KEYBYTES );
+
+    if( 0 != memcmp( hash, blake2b_keyed_kat[i], BLAKE2B_OUTBYTES ) )
+    {
+      goto fail;
+    }
+  }
+
+  /* Test streaming API */
+  for(step = 1; step < BLAKE2B_BLOCKBYTES; ++step) {
+    for (i = 0; i < BLAKE2_KAT_LENGTH; ++i) {
+      uint8_t hash[BLAKE2B_OUTBYTES];
+      blake2b_state S;
+      uint8_t * p = buf;
+      size_t mlen = i;
+      int err = 0;
+
+      if( (err = blake2b_init_key(&S, BLAKE2B_OUTBYTES, key, BLAKE2B_KEYBYTES)) < 0 ) {
+        goto fail;
+      }
+
+      while (mlen >= step) {
+        if ( (err = blake2b_update(&S, p, step)) < 0 ) {
+          goto fail;
+        }
+        mlen -= step;
+        p += step;
+      }
+      if ( (err = blake2b_update(&S, p, mlen)) < 0) {
+        goto fail;
+      }
+      if ( (err = blake2b_final(&S, hash, BLAKE2B_OUTBYTES)) < 0) {
+        goto fail;
+      }
+
+      if (0 != memcmp(hash, blake2b_keyed_kat[i], BLAKE2B_OUTBYTES)) {
+        goto fail;
+      }
+    }
+  }
+
+  puts( "ok" );
+  return 0;
+fail:
+  puts("error");
+  return -1;
+}
+#endif
diff --git a/src/local.mk b/src/local.mk
index 9e36ad9bd..c5898cca1 100644
--- a/src/local.mk
+++ b/src/local.mk
@@ -393,6 +393,12 @@ src_sha384sum_SOURCES = src/md5sum.c
 src_sha384sum_CPPFLAGS = -DHASH_ALGO_SHA384=1 $(AM_CPPFLAGS)
 src_sha512sum_SOURCES = src/md5sum.c
 src_sha512sum_CPPFLAGS = -DHASH_ALGO_SHA512=1 $(AM_CPPFLAGS)
+src_b2sum_CPPFLAGS = -include config.h -DHASH_ALGO_BLAKE2=1 \
+		     $(AM_CPPFLAGS)
+src_b2sum_SOURCES = src/md5sum.c \
+		    src/blake2/blake2.h src/blake2/blake2-impl.h \
+		    src/blake2/blake2b-ref.c \
+		    src/blake2/b2sum.c src/blake2/b2sum.h
 
 src_base64_CPPFLAGS = -DBASE_TYPE=64 $(AM_CPPFLAGS)
 src_base32_SOURCES = src/base64.c
diff --git a/src/md5sum.c b/src/md5sum.c
index 6e85cb150..8e2160967 100644
--- a/src/md5sum.c
+++ b/src/md5sum.c
@@ -22,7 +22,14 @@
 #include <sys/types.h>
 
 #include "system.h"
+#include "argmatch.h"
+#include "quote.h"
+#include "xdectoint.h"
+#include "xstrtol.h"
 
+#if HASH_ALGO_BLAKE2
+# include "blake2/b2sum.h"
+#endif
 #if HASH_ALGO_MD5
 # include "md5.h"
 #endif
@@ -49,6 +56,13 @@
 # define DIGEST_BITS 128
 # define DIGEST_REFERENCE "RFC 1321"
 # define DIGEST_ALIGN 4
+#elif HASH_ALGO_BLAKE2
+# define PROGRAM_NAME "b2sum"
+# define DIGEST_TYPE_STRING "BLAKE2"
+# define DIGEST_STREAM blake2fns[b2_algorithm]
+# define DIGEST_BITS 512
+# define DIGEST_REFERENCE "RFC 7693"
+# define DIGEST_ALIGN 8
 #elif HASH_ALGO_SHA1
 # define PROGRAM_NAME "sha1sum"
 # define DIGEST_TYPE_STRING "SHA1"
@@ -88,20 +102,30 @@
 # error "Can't decide which hash algorithm to compile."
 #endif
 
-#define DIGEST_HEX_BYTES (DIGEST_BITS / 4)
-#define DIGEST_BIN_BYTES (DIGEST_BITS / 8)
-
-#define AUTHORS \
+#if HASH_ALGO_BLAKE2
+# define AUTHORS \
+  proper_name ("Padraig Brady"), \
+  proper_name ("Samuel Neves")
+#else
+# define AUTHORS \
   proper_name ("Ulrich Drepper"), \
   proper_name ("Scott Miller"), \
   proper_name ("David Madore")
+# define DIGEST_HEX_BYTES (DIGEST_BITS / 4)
+#endif
+#define DIGEST_BIN_BYTES (DIGEST_BITS / 8)
+
 
 /* The minimum length of a valid digest line.  This length does
    not include any newline character at the end of a line.  */
-#define MIN_DIGEST_LINE_LENGTH \
-  (DIGEST_HEX_BYTES /* length of hexadecimal message digest */ \
-   + 1 /* blank */ \
-   + 1 /* minimum filename length */ )
+#if HASH_ALGO_BLAKE2
+# define MIN_DIGEST_LINE_LENGTH 3 /* With -l 8.  */
+#else
+# define MIN_DIGEST_LINE_LENGTH \
+   (DIGEST_HEX_BYTES /* length of hexadecimal message digest */ \
+    + 1 /* blank */ \
+    + 1 /* minimum filename length */ )
+#endif
 
 /* True if any of the files read were the standard input. */
 static bool have_read_stdin;
@@ -133,6 +157,38 @@ static bool strict = false;
 /* Whether a BSD reversed format checksum is detected.  */
 static int bsd_reversed = -1;
 
+#if HASH_ALGO_BLAKE2
+static char const *const algorithm_in_string[] =
+{
+  "blake2b", NULL
+};
+static char const *const algorithm_out_string[] =
+{
+  "BLAKE2b", NULL
+};
+enum Algorithm
+{
+  BLAKE2b
+};
+static enum Algorithm const algorithm[] =
+{
+  BLAKE2b
+};
+ARGMATCH_VERIFY (algorithm_in_string, algorithm);
+ARGMATCH_VERIFY (algorithm_out_string, algorithm);
+
+static enum Algorithm b2_algorithm;
+static uintmax_t b2_length;
+static blake2fn blake2fns[]=
+{
+  blake2b_stream
+};
+static uintmax_t blake2_max_len[]=
+{
+  BLAKE2B_OUTBYTES
+};
+#endif /* HASH_ALGO_BLAKE2 */
+
 /* For long options that have no equivalent short option, use a
    non-character as a pseudo short option, starting with CHAR_MAX + 1.  */
 enum
@@ -146,6 +202,9 @@ enum
 
 static struct option const long_options[] =
 {
+#if HASH_ALGO_BLAKE2
+  { "length", required_argument, NULL, 'l'},
+#endif
   { "binary", no_argument, NULL, 'b' },
   { "check", no_argument, NULL, 'c' },
   { "ignore-missing", no_argument, NULL, IGNORE_MISSING_OPTION},
@@ -176,7 +235,6 @@ Print or check %s (%d-bit) checksums.\n\
               DIGEST_BITS);
 
       emit_stdin_note ();
-
       if (O_BINARY)
         fputs (_("\
 \n\
@@ -187,9 +245,16 @@ Print or check %s (%d-bit) checksums.\n\
 \n\
   -b, --binary         read in binary mode\n\
 "), stdout);
+
       printf (_("\
   -c, --check          read %s sums from the FILEs and check them\n"),
               DIGEST_TYPE_STRING);
+#if HASH_ALGO_BLAKE2
+        fputs (_("\
+  -l, --length         digest length in bits; must not exceed the maximum for\n\
+                       the blake2 algorithm and must be a multiple of 8\n\
+"), stdout);
+#endif
       fputs (_("\
       --tag            create a BSD-style checksum\n\
 "), stdout);
@@ -350,15 +415,51 @@ split_3 (char *s, size_t s_len,
   algo_name_len = strlen (DIGEST_TYPE_STRING);
   if (STREQ_LEN (s + i, DIGEST_TYPE_STRING, algo_name_len))
     {
-      if (s[i + algo_name_len] == ' ')
+      i += algo_name_len;
+#if HASH_ALGO_BLAKE2
+      /* Terminate and match algorithm name.  */
+      char const *algo_name = &s[i - algo_name_len];
+      while (! ISWHITE (s[i]) && s[i] != '-' && s[i] != '(')
         ++i;
-      if (s[i + algo_name_len] == '(')
+      bool length_specified = s[i] == '-';
+      bool openssl_format = s[i] == '('; /* and no length_specified */
+      s[i++] = '\0';
+      ptrdiff_t algo = argmatch (algo_name, algorithm_out_string, NULL, 0);
+      if (algo < 0)
+        return false;
+      else
+        b2_algorithm = algo;
+      if (openssl_format)
+        s[--i] = '(';
+
+      if (length_specified)
         {
+          unsigned long int tmp_ulong;
+          if (xstrtoul (s + i, NULL, 0, &tmp_ulong, NULL) == LONGINT_OK
+              && 0 < tmp_ulong && tmp_ulong <= blake2_max_len[b2_algorithm] * 8
+              && tmp_ulong % 8 == 0)
+            b2_length = tmp_ulong;
+          else
+            return false;
+
+          while (ISDIGIT (s[i]))
+            ++i;
+        }
+      else
+        b2_length = blake2_max_len[b2_algorithm] * 8;
+
+      digest_hex_bytes = b2_length / 4;
+#endif
+      if (s[i] == ' ')
+        ++i;
+      if (s[i] == '(')
+        {
+          ++i;
           *binary = 0;
-          return bsd_split_3 (s +      i + algo_name_len + 1,
-                              s_len - (i + algo_name_len + 1),
+          return bsd_split_3 (s + i, s_len - i,
                               hex_digest, file_name, escaped_filename);
         }
+      return false;
     }
 
   /* Ignore this line if it is too short.
@@ -370,6 +471,18 @@ split_3 (char *s, size_t s_len,
 
   *hex_digest = (unsigned char *) &s[i];
 
+#if HASH_ALGO_BLAKE2
+  /* Auto determine length.  */
+  unsigned char const *hp = *hex_digest;
+  digest_hex_bytes = 0;
+  while (isxdigit (*hp++))
+    digest_hex_bytes++;
+  if (digest_hex_bytes < 2 || digest_hex_bytes % 2
+      || blake2_max_len[b2_algorithm] * 2 < digest_hex_bytes)
+    return false;
+  b2_length = digest_hex_bytes * 4;
+#endif
+
   /* The first field has to be the n-character hexadecimal
      representation of the message digest.  If it is not followed
      immediately by a white space it's an error.  */
@@ -505,7 +618,11 @@ digest_file (const char *filename, int *binary, unsigned char *bin_result,
 
   fadvise (fp, FADVISE_SEQUENTIAL);
 
+#if HASH_ALGO_BLAKE2
+  err = DIGEST_STREAM (fp, bin_result, b2_length / 8);
+#else
   err = DIGEST_STREAM (fp, bin_result);
+#endif
   if (err)
     {
       error (0, errno, "%s", quotef (filename));
@@ -758,9 +875,28 @@ main (int argc, char **argv)
      so that processes running in parallel do not intersperse their output.  */
   setvbuf (stdout, NULL, _IOLBF, 0);
 
-  while ((opt = getopt_long (argc, argv, "bctw", long_options, NULL)) != -1)
+#if HASH_ALGO_BLAKE2
+  const char* short_opts = "l:bctw";
+  const char* b2_length_str = "";
+#else
+  const char* short_opts = "bctw";
+#endif
+
+  while ((opt = getopt_long (argc, argv, short_opts, long_options, NULL)) != -1)
     switch (opt)
       {
+#if HASH_ALGO_BLAKE2
+      case 'l':
+        b2_length = xdectoumax (optarg, 0, UINTMAX_MAX, "",
+                                _("invalid length"), 0);
+        b2_length_str = optarg;
+        if (b2_length % 8 != 0)
+          {
+            error (0, 0, _("invalid length: %s"), quote (b2_length_str));
+            die (EXIT_FAILURE, 0, _("length is not a multiple of 8"));
+          }
+        break;
+#endif
       case 'b':
         binary = 1;
         break;
@@ -802,7 +938,21 @@ main (int argc, char **argv)
       }
 
   min_digest_line_length = MIN_DIGEST_LINE_LENGTH;
+#if HASH_ALGO_BLAKE2
+  if (b2_length > blake2_max_len[b2_algorithm] * 8)
+    {
+      error (0, 0, _("invalid length: %s"), quote (b2_length_str));
+      die (EXIT_FAILURE, 0,
+           _("maximum digest length for %s is %"PRIuMAX" bits"),
+           quote (algorithm_in_string[b2_algorithm]),
+           blake2_max_len[b2_algorithm] * 8);
+    }
+  if (b2_length == 0 && ! do_check)
+    b2_length = blake2_max_len[b2_algorithm] * 8;
+  digest_hex_bytes = b2_length / 4;
+#else
   digest_hex_bytes = DIGEST_HEX_BYTES;
+#endif
 
   if (prefix_tag && !binary)
    {
@@ -901,7 +1051,13 @@ main (int argc, char **argv)
                   if (needs_escape)
                     putchar ('\\');
 
+#if HASH_ALGO_BLAKE2
+                  fputs (algorithm_out_string[b2_algorithm], stdout);
+                  if (b2_length < blake2_max_len[b2_algorithm] * 8)
+                    printf ("-%"PRIuMAX, b2_length);
+#else
                   fputs (DIGEST_TYPE_STRING, stdout);
+#endif
                   fputs (" (", stdout);
                   print_filename (file, needs_escape);
                   fputs (") = ", stdout);