Add ccm_encrypt_and_tag()
diff --git a/library/ccm.c b/library/ccm.c
index 453edfb..4a8decf 100644
--- a/library/ccm.c
+++ b/library/ccm.c
@@ -81,6 +81,206 @@
memset( ctx, 0, sizeof( ccm_context ) );
}
+#define UPDATE_CBC_MAC( src ) \
+{ \
+ size_t olen; \
+ \
+ for( i = 0; i < 16; i++ ) \
+ src[i] ^= y[i]; \
+ \
+ if( ( ret = cipher_update( &ctx->cipher_ctx, src, 16, \
+ y, &olen ) ) != 0 ) \
+ { \
+ return( ret ); \
+ } \
+}
+
+#define CTR_CRYPT_BLOCK( dst, src ) \
+{ \
+ size_t olen; \
+ \
+ if( ( ret = cipher_update( &ctx->cipher_ctx, ctr, 16, \
+ dst, &olen ) ) != 0 ) \
+ { \
+ return( ret ); \
+ } \
+ \
+ for( i = 0; i < 16; i++ ) \
+ dst[i] ^= src[i]; \
+}
+
+/*
+ * Authenticated encryption
+ */
+int ccm_crypt_and_tag( ccm_context *ctx, size_t length,
+ const unsigned char *iv, size_t iv_len,
+ const unsigned char *add, size_t add_len,
+ const unsigned char *input, unsigned char *output,
+ unsigned char *tag, size_t tag_len )
+{
+ int ret;
+ unsigned char i;
+ unsigned char q = 16 - 1 - iv_len;
+ size_t len_left;
+ unsigned char b[16];
+ unsigned char y[16];
+ unsigned char ctr[16];
+ const unsigned char *src;
+ unsigned char *dst;
+
+ /*
+ * Check length requirements: SP800-38C A.1
+ * Additional requirement: a < 2^16 - 2^8 to simplify the code.
+ * 'length' checked later (when writing it to the first block)
+ */
+ if( tag_len < 4 || tag_len > 16 || tag_len % 2 != 0 )
+ return( POLARSSL_ERR_CCM_BAD_INPUT );
+
+ /* Also implies q is within bounds */
+ if( iv_len < 7 || iv_len > 13 )
+ return( POLARSSL_ERR_CCM_BAD_INPUT );
+
+ if( add_len > 0xFF00 )
+ return( POLARSSL_ERR_CCM_BAD_INPUT );
+
+ /*
+ * First block B_0:
+ * 0 .. 0 flags
+ * 1 .. iv_len nonce (aka iv)
+ * iv_len+1 .. 15 length
+ *
+ * With flags as (bits):
+ * 7 0
+ * 6 add present?
+ * 5 .. 3 (t - 2) / 2
+ * 2 .. 0 q - 1
+ */
+ b[0] = 0;
+ b[0] |= ( add_len > 0 ) << 6;
+ b[0] |= ( ( tag_len - 2 ) / 2 ) << 3;
+ b[0] |= q - 1;
+
+ memcpy( b + 1, iv, iv_len );
+
+ for( i = 0, len_left = length; i < q; i++, len_left >>= 8 )
+ b[15-i] = (unsigned char)( len_left & 0xFF );
+
+ if( len_left > 0 )
+ return( POLARSSL_ERR_CCM_BAD_INPUT );
+
+
+ /* Start CBC-MAC with first block */
+ memset( y, 0, 16 );
+ UPDATE_CBC_MAC( b );
+
+ /*
+ * If there is additional data, update CBC-MAC with
+ * add_len, add, 0 (padding to a block boundary)
+ */
+ if( add_len > 0 )
+ {
+ size_t use_len;
+ len_left = add_len;
+ src = add;
+
+ memset( b, 0, 16 );
+ b[0] = (unsigned char)( ( add_len >> 8 ) & 0xFF );
+ b[1] = (unsigned char)( ( add_len ) & 0xFF );
+
+ use_len = len_left < 16 - 2 ? len_left : 16 - 2;
+ memcpy( b + 2, src, use_len );
+ len_left -= use_len;
+ src += use_len;
+
+ UPDATE_CBC_MAC( b );
+
+ while( len_left > 16 )
+ {
+ memcpy( b, src, 16 );
+ UPDATE_CBC_MAC( b );
+
+ len_left -= 16;
+ src += 16;
+ }
+
+ if( len_left > 0 )
+ {
+ memset( b, 0, 16 );
+ memcpy( b, src, len_left );
+
+ UPDATE_CBC_MAC( b );
+ }
+ }
+
+ /*
+ * Counter block:
+ * 0 .. 0 flags
+ * 1 .. iv_len nonce (aka iv)
+ * iv_len+1 .. 15 counter (initially 1)
+ *
+ * With flags as (bits):
+ * 7 .. 3 0
+ * 2 .. 0 q - 1
+ */
+ ctr[0] = q - 1;
+ memcpy( ctr + 1, iv, iv_len );
+ memset( ctr + 1 + iv_len, 0, q );
+ ctr[15] = 1;
+
+ len_left = length;
+ src = input;
+ dst = output;
+
+ /*
+ * Authenticate and encrypt message
+ */
+ while( len_left > 16 )
+ {
+ memcpy( b, src, 16 );
+ UPDATE_CBC_MAC( b );
+ CTR_CRYPT_BLOCK( dst, src );
+
+ dst += 16;
+ src += 16;
+ len_left -= 16;
+
+ for( i = 0; i < q; i++ )
+ if( ++ctr[15-i] != 0 )
+ break;
+ }
+
+ if( len_left > 0 )
+ {
+ unsigned char mask[16];
+ size_t olen;
+
+ memset( b, 0, 16 );
+ memcpy( b, src, len_left );
+
+ UPDATE_CBC_MAC( b );
+
+ if( ( ret = cipher_update( &ctx->cipher_ctx, ctr, 16,
+ mask, &olen ) ) != 0 )
+ {
+ return( ret );
+ }
+
+ for( i = 0; i < len_left; i++ )
+ dst[i] = src[i] ^ mask[i];
+ }
+
+ /*
+ * Authentication: reset counter and encrypt internal tag
+ */
+ for( i = 0; i < q; i++ )
+ ctr[15-i] = 0;
+
+ CTR_CRYPT_BLOCK( b, y );
+ memcpy( tag, b, tag_len );
+
+ return( 0 );
+}
+
#if defined(POLARSSL_SELF_TEST) && defined(POLARSSL_AES_C)
@@ -90,10 +290,92 @@
#define polarssl_printf printf
#endif
+/*
+ * Examples 1 to 3 from SP800-38C Appendix C
+ */
+
+#define NB_TESTS 3
+
+/*
+ * The data is the same for all tests, only the used length changes
+ */
+static const unsigned char key[] = {
+ 0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47,
+ 0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f
+};
+
+static const unsigned char iv[] = {
+ 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
+ 0x18, 0x19, 0x1a, 0x1b
+};
+
+static const unsigned char ad[] = {
+ 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
+ 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
+ 0x10, 0x11, 0x12, 0x13
+};
+
+static const unsigned char msg[] = {
+ 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,
+ 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
+ 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37,
+};
+
+static const size_t iv_len [NB_TESTS] = { 7, 8, 12 };
+static const size_t add_len[NB_TESTS] = { 8, 16, 20 };
+static const size_t msg_len[NB_TESTS] = { 4, 16, 24 };
+static const size_t tag_len[NB_TESTS] = { 4, 6, 8 };
+
+static const unsigned char res[NB_TESTS][32] = {
+ { 0x71, 0x62, 0x01, 0x5b, 0x4d, 0xac, 0x25, 0x5d },
+ { 0xd2, 0xa1, 0xf0, 0xe0, 0x51, 0xea, 0x5f, 0x62,
+ 0x08, 0x1a, 0x77, 0x92, 0x07, 0x3d, 0x59, 0x3d,
+ 0x1f, 0xc6, 0x4f, 0xbf, 0xac, 0xcd },
+ { 0xe3, 0xb2, 0x01, 0xa9, 0xf5, 0xb7, 0x1a, 0x7a,
+ 0x9b, 0x1c, 0xea, 0xec, 0xcd, 0x97, 0xe7, 0x0b,
+ 0x61, 0x76, 0xaa, 0xd9, 0xa4, 0x42, 0x8a, 0xa5,
+ 0x48, 0x43, 0x92, 0xfb, 0xc1, 0xb0, 0x99, 0x51 }
+};
+
int ccm_self_test( int verbose )
{
- if( verbose != 0 )
- polarssl_printf( " CCM: skip\n" );
+ ccm_context ctx;
+ unsigned char out[32];
+ size_t i;
+ int ret;
+
+ if( ccm_init( &ctx, POLARSSL_CIPHER_ID_AES, key, 8 * sizeof key ) != 0 )
+ {
+ if( verbose != 0 )
+ polarssl_printf( " CCM: setup failed" );
+
+ return( 1 );
+ }
+
+ for( i = 0; i < NB_TESTS; i++ )
+ {
+ if( verbose != 0 )
+ polarssl_printf( " CCM-AES #%u: ", (unsigned int) i + 1 );
+
+ ret = ccm_crypt_and_tag( &ctx, msg_len[i],
+ iv, iv_len[i], ad, add_len[i],
+ msg, out,
+ out + msg_len[i], tag_len[i] );
+
+ if( ret != 0 ||
+ memcmp( out, res[i], msg_len[i] + tag_len[i] ) != 0 )
+ {
+ if( verbose != 0 )
+ polarssl_printf( "failed\n" );
+
+ return( 1 );
+ }
+
+ if( verbose != 0 )
+ polarssl_printf( "passed\n" );
+ }
+
+ ccm_free( &ctx );
if( verbose != 0 )
polarssl_printf( "\n" );
