Merge pull request #3973 from stroebeljc/development
Fixed seed variable concatenation pointer.
diff --git a/ChangeLog.d/issue3819.txt b/ChangeLog.d/issue3819.txt
new file mode 100644
index 0000000..e41520f
--- /dev/null
+++ b/ChangeLog.d/issue3819.txt
@@ -0,0 +1,10 @@
+Security
+ * Fix a security reduction in CTR_DRBG when the initial seeding obtained a
+ nonce from entropy. Applications were affected if they called
+ mbedtls_ctr_drbg_set_nonce_len(), if they called
+ mbedtls_ctr_drbg_set_entropy_len() with a size that was 3/2 times the key
+ length, or when the entropy module uses SHA-256 and CTR_DRBG uses AES-256.
+ In such cases, a random nonce was necessary to achieve the advertised
+ security strength, but the code incorrectly used a constant instead of
+ entropy from the nonce.
+ Found by John Stroebel in #3819 and fixed in #3973.
diff --git a/library/ctr_drbg.c b/library/ctr_drbg.c
index 023aac5..3815dc7 100644
--- a/library/ctr_drbg.c
+++ b/library/ctr_drbg.c
@@ -394,7 +394,7 @@
/* Gather entropy for a nonce if requested. */
if( nonce_len != 0 )
{
- if( 0 != ctx->f_entropy( ctx->p_entropy, seed, nonce_len ) )
+ if( 0 != ctx->f_entropy( ctx->p_entropy, seed + seedlen, nonce_len ) )
{
return( MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED );
}
@@ -684,54 +684,134 @@
#if defined(MBEDTLS_SELF_TEST)
-static const unsigned char entropy_source_pr[96] =
- { 0xc1, 0x80, 0x81, 0xa6, 0x5d, 0x44, 0x02, 0x16,
- 0x19, 0xb3, 0xf1, 0x80, 0xb1, 0xc9, 0x20, 0x02,
- 0x6a, 0x54, 0x6f, 0x0c, 0x70, 0x81, 0x49, 0x8b,
- 0x6e, 0xa6, 0x62, 0x52, 0x6d, 0x51, 0xb1, 0xcb,
- 0x58, 0x3b, 0xfa, 0xd5, 0x37, 0x5f, 0xfb, 0xc9,
- 0xff, 0x46, 0xd2, 0x19, 0xc7, 0x22, 0x3e, 0x95,
- 0x45, 0x9d, 0x82, 0xe1, 0xe7, 0x22, 0x9f, 0x63,
- 0x31, 0x69, 0xd2, 0x6b, 0x57, 0x47, 0x4f, 0xa3,
- 0x37, 0xc9, 0x98, 0x1c, 0x0b, 0xfb, 0x91, 0x31,
- 0x4d, 0x55, 0xb9, 0xe9, 0x1c, 0x5a, 0x5e, 0xe4,
- 0x93, 0x92, 0xcf, 0xc5, 0x23, 0x12, 0xd5, 0x56,
- 0x2c, 0x4a, 0x6e, 0xff, 0xdc, 0x10, 0xd0, 0x68 };
-
-static const unsigned char entropy_source_nopr[64] =
- { 0x5a, 0x19, 0x4d, 0x5e, 0x2b, 0x31, 0x58, 0x14,
- 0x54, 0xde, 0xf6, 0x75, 0xfb, 0x79, 0x58, 0xfe,
- 0xc7, 0xdb, 0x87, 0x3e, 0x56, 0x89, 0xfc, 0x9d,
- 0x03, 0x21, 0x7c, 0x68, 0xd8, 0x03, 0x38, 0x20,
- 0xf9, 0xe6, 0x5e, 0x04, 0xd8, 0x56, 0xf3, 0xa9,
- 0xc4, 0x4a, 0x4c, 0xbd, 0xc1, 0xd0, 0x08, 0x46,
- 0xf5, 0x98, 0x3d, 0x77, 0x1c, 0x1b, 0x13, 0x7e,
- 0x4e, 0x0f, 0x9d, 0x8e, 0xf4, 0x09, 0xf9, 0x2e };
-
-static const unsigned char nonce_pers_pr[16] =
- { 0xd2, 0x54, 0xfc, 0xff, 0x02, 0x1e, 0x69, 0xd2,
- 0x29, 0xc9, 0xcf, 0xad, 0x85, 0xfa, 0x48, 0x6c };
-
-static const unsigned char nonce_pers_nopr[16] =
- { 0x1b, 0x54, 0xb8, 0xff, 0x06, 0x42, 0xbf, 0xf5,
- 0x21, 0xf1, 0x5c, 0x1c, 0x0b, 0x66, 0x5f, 0x3f };
+/* The CTR_DRBG NIST test vectors used here are available at
+ * https://csrc.nist.gov/CSRC/media/Projects/Cryptographic-Algorithm-Validation-Program/documents/drbg/drbgtestvectors.zip
+ *
+ * The parameters used to derive the test data are:
+ *
+ * [AES-128 use df]
+ * [PredictionResistance = True/False]
+ * [EntropyInputLen = 128]
+ * [NonceLen = 64]
+ * [PersonalizationStringLen = 128]
+ * [AdditionalInputLen = 0]
+ * [ReturnedBitsLen = 512]
+ *
+ * [AES-256 use df]
+ * [PredictionResistance = True/False]
+ * [EntropyInputLen = 256]
+ * [NonceLen = 128]
+ * [PersonalizationStringLen = 256]
+ * [AdditionalInputLen = 0]
+ * [ReturnedBitsLen = 512]
+ *
+ */
#if defined(MBEDTLS_CTR_DRBG_USE_128_BIT_KEY)
-static const unsigned char result_pr[16] =
- { 0x95, 0x3c, 0xa5, 0xbd, 0x44, 0x1, 0x34, 0xb7,
- 0x13, 0x58, 0x3e, 0x6a, 0x6c, 0x7e, 0x88, 0x8a };
+static const unsigned char entropy_source_pr[] =
+ { 0x04, 0xd9, 0x49, 0xa6, 0xdc, 0xe8, 0x6e, 0xbb,
+ 0xf1, 0x08, 0x77, 0x2b, 0x9e, 0x08, 0xca, 0x92,
+ 0x65, 0x16, 0xda, 0x99, 0xa2, 0x59, 0xf3, 0xe8,
+ 0x38, 0x7e, 0x3f, 0x6b, 0x51, 0x70, 0x7b, 0x20,
+ 0xec, 0x53, 0xd0, 0x66, 0xc3, 0x0f, 0xe3, 0xb0,
+ 0xe0, 0x86, 0xa6, 0xaa, 0x5f, 0x72, 0x2f, 0xad,
+ 0xf7, 0xef, 0x06, 0xb8, 0xd6, 0x9c, 0x9d, 0xe8 };
-static const unsigned char result_nopr[16] =
- { 0x6c, 0x25, 0x27, 0x95, 0xa3, 0x62, 0xd6, 0xdb,
- 0x90, 0xfd, 0x69, 0xb5, 0x42, 0x9, 0x4b, 0x84 };
+static const unsigned char entropy_source_nopr[] =
+ { 0x07, 0x0d, 0x59, 0x63, 0x98, 0x73, 0xa5, 0x45,
+ 0x27, 0x38, 0x22, 0x7b, 0x76, 0x85, 0xd1, 0xa9,
+ 0x74, 0x18, 0x1f, 0x3c, 0x22, 0xf6, 0x49, 0x20,
+ 0x4a, 0x47, 0xc2, 0xf3, 0x85, 0x16, 0xb4, 0x6f,
+ 0x00, 0x2e, 0x71, 0xda, 0xed, 0x16, 0x9b, 0x5c };
+
+static const unsigned char pers_pr[] =
+ { 0xbf, 0xa4, 0x9a, 0x8f, 0x7b, 0xd8, 0xb1, 0x7a,
+ 0x9d, 0xfa, 0x45, 0xed, 0x21, 0x52, 0xb3, 0xad };
+
+static const unsigned char pers_nopr[] =
+ { 0x4e, 0x61, 0x79, 0xd4, 0xc2, 0x72, 0xa1, 0x4c,
+ 0xf1, 0x3d, 0xf6, 0x5e, 0xa3, 0xa6, 0xe5, 0x0f };
+
+static const unsigned char result_pr[] =
+ { 0xc9, 0x0a, 0xaf, 0x85, 0x89, 0x71, 0x44, 0x66,
+ 0x4f, 0x25, 0x0b, 0x2b, 0xde, 0xd8, 0xfa, 0xff,
+ 0x52, 0x5a, 0x1b, 0x32, 0x5e, 0x41, 0x7a, 0x10,
+ 0x1f, 0xef, 0x1e, 0x62, 0x23, 0xe9, 0x20, 0x30,
+ 0xc9, 0x0d, 0xad, 0x69, 0xb4, 0x9c, 0x5b, 0xf4,
+ 0x87, 0x42, 0xd5, 0xae, 0x5e, 0x5e, 0x43, 0xcc,
+ 0xd9, 0xfd, 0x0b, 0x93, 0x4a, 0xe3, 0xd4, 0x06,
+ 0x37, 0x36, 0x0f, 0x3f, 0x72, 0x82, 0x0c, 0xcf };
+
+static const unsigned char result_nopr[] =
+ { 0x31, 0xc9, 0x91, 0x09, 0xf8, 0xc5, 0x10, 0x13,
+ 0x3c, 0xd3, 0x96, 0xf9, 0xbc, 0x2c, 0x12, 0xc0,
+ 0x7c, 0xc1, 0x61, 0x5f, 0xa3, 0x09, 0x99, 0xaf,
+ 0xd7, 0xf2, 0x36, 0xfd, 0x40, 0x1a, 0x8b, 0xf2,
+ 0x33, 0x38, 0xee, 0x1d, 0x03, 0x5f, 0x83, 0xb7,
+ 0xa2, 0x53, 0xdc, 0xee, 0x18, 0xfc, 0xa7, 0xf2,
+ 0xee, 0x96, 0xc6, 0xc2, 0xcd, 0x0c, 0xff, 0x02,
+ 0x76, 0x70, 0x69, 0xaa, 0x69, 0xd1, 0x3b, 0xe8 };
#else /* MBEDTLS_CTR_DRBG_USE_128_BIT_KEY */
-static const unsigned char result_pr[16] =
- { 0x34, 0x01, 0x16, 0x56, 0xb4, 0x29, 0x00, 0x8f,
- 0x35, 0x63, 0xec, 0xb5, 0xf2, 0x59, 0x07, 0x23 };
-static const unsigned char result_nopr[16] =
- { 0xa0, 0x54, 0x30, 0x3d, 0x8a, 0x7e, 0xa9, 0x88,
- 0x9d, 0x90, 0x3e, 0x07, 0x7c, 0x6f, 0x21, 0x8f };
+static const unsigned char entropy_source_pr[] =
+ { 0xca, 0x58, 0xfd, 0xf2, 0xb9, 0x77, 0xcb, 0x49,
+ 0xd4, 0xe0, 0x5b, 0xe2, 0x39, 0x50, 0xd9, 0x8a,
+ 0x6a, 0xb3, 0xc5, 0x2f, 0xdf, 0x74, 0xd5, 0x85,
+ 0x8f, 0xd1, 0xba, 0x64, 0x54, 0x7b, 0xdb, 0x1e,
+ 0xc5, 0xea, 0x24, 0xc0, 0xfa, 0x0c, 0x90, 0x15,
+ 0x09, 0x20, 0x92, 0x42, 0x32, 0x36, 0x45, 0x45,
+ 0x7d, 0x20, 0x76, 0x6b, 0xcf, 0xa2, 0x15, 0xc8,
+ 0x2f, 0x9f, 0xbc, 0x88, 0x3f, 0x80, 0xd1, 0x2c,
+ 0xb7, 0x16, 0xd1, 0x80, 0x9e, 0xe1, 0xc9, 0xb3,
+ 0x88, 0x1b, 0x21, 0x45, 0xef, 0xa1, 0x7f, 0xce,
+ 0xc8, 0x92, 0x35, 0x55, 0x2a, 0xd9, 0x1d, 0x8e,
+ 0x12, 0x38, 0xac, 0x01, 0x4e, 0x38, 0x18, 0x76,
+ 0x9c, 0xf2, 0xb6, 0xd4, 0x13, 0xb6, 0x2c, 0x77,
+ 0xc0, 0xe7, 0xe6, 0x0c, 0x47, 0x44, 0x95, 0xbe };
+
+static const unsigned char entropy_source_nopr[] =
+ { 0x4c, 0xfb, 0x21, 0x86, 0x73, 0x34, 0x6d, 0x9d,
+ 0x50, 0xc9, 0x22, 0xe4, 0x9b, 0x0d, 0xfc, 0xd0,
+ 0x90, 0xad, 0xf0, 0x4f, 0x5c, 0x3b, 0xa4, 0x73,
+ 0x27, 0xdf, 0xcd, 0x6f, 0xa6, 0x3a, 0x78, 0x5c,
+ 0x01, 0x69, 0x62, 0xa7, 0xfd, 0x27, 0x87, 0xa2,
+ 0x4b, 0xf6, 0xbe, 0x47, 0xef, 0x37, 0x83, 0xf1,
+ 0xb7, 0xec, 0x46, 0x07, 0x23, 0x63, 0x83, 0x4a,
+ 0x1b, 0x01, 0x33, 0xf2, 0xc2, 0x38, 0x91, 0xdb,
+ 0x4f, 0x11, 0xa6, 0x86, 0x51, 0xf2, 0x3e, 0x3a,
+ 0x8b, 0x1f, 0xdc, 0x03, 0xb1, 0x92, 0xc7, 0xe7 };
+
+static const unsigned char pers_pr[] =
+ { 0x5a, 0x70, 0x95, 0xe9, 0x81, 0x40, 0x52, 0x33,
+ 0x91, 0x53, 0x7e, 0x75, 0xd6, 0x19, 0x9d, 0x1e,
+ 0xad, 0x0d, 0xc6, 0xa7, 0xde, 0x6c, 0x1f, 0xe0,
+ 0xea, 0x18, 0x33, 0xa8, 0x7e, 0x06, 0x20, 0xe9 };
+
+static const unsigned char pers_nopr[] =
+ { 0x88, 0xee, 0xb8, 0xe0, 0xe8, 0x3b, 0xf3, 0x29,
+ 0x4b, 0xda, 0xcd, 0x60, 0x99, 0xeb, 0xe4, 0xbf,
+ 0x55, 0xec, 0xd9, 0x11, 0x3f, 0x71, 0xe5, 0xeb,
+ 0xcb, 0x45, 0x75, 0xf3, 0xd6, 0xa6, 0x8a, 0x6b };
+
+static const unsigned char result_pr[] =
+ { 0xce, 0x2f, 0xdb, 0xb6, 0xd9, 0xb7, 0x39, 0x85,
+ 0x04, 0xc5, 0xc0, 0x42, 0xc2, 0x31, 0xc6, 0x1d,
+ 0x9b, 0x5a, 0x59, 0xf8, 0x7e, 0x0d, 0xcc, 0x62,
+ 0x7b, 0x65, 0x11, 0x55, 0x10, 0xeb, 0x9e, 0x3d,
+ 0xa4, 0xfb, 0x1c, 0x6a, 0x18, 0xc0, 0x74, 0xdb,
+ 0xdd, 0xe7, 0x02, 0x23, 0x63, 0x21, 0xd0, 0x39,
+ 0xf9, 0xa7, 0xc4, 0x52, 0x84, 0x3b, 0x49, 0x40,
+ 0x72, 0x2b, 0xb0, 0x6c, 0x9c, 0xdb, 0xc3, 0x43 };
+
+static const unsigned char result_nopr[] =
+ { 0xa5, 0x51, 0x80, 0xa1, 0x90, 0xbe, 0xf3, 0xad,
+ 0xaf, 0x28, 0xf6, 0xb7, 0x95, 0xe9, 0xf1, 0xf3,
+ 0xd6, 0xdf, 0xa1, 0xb2, 0x7d, 0xd0, 0x46, 0x7b,
+ 0x0c, 0x75, 0xf5, 0xfa, 0x93, 0x1e, 0x97, 0x14,
+ 0x75, 0xb2, 0x7c, 0xae, 0x03, 0xa2, 0x96, 0x54,
+ 0xe2, 0xf4, 0x09, 0x66, 0xea, 0x33, 0x64, 0x30,
+ 0x40, 0xd1, 0x40, 0x0f, 0xe6, 0x77, 0x87, 0x3a,
+ 0xf8, 0x09, 0x7c, 0x1f, 0xe9, 0xf0, 0x02, 0x98 };
#endif /* MBEDTLS_CTR_DRBG_USE_128_BIT_KEY */
static size_t test_offset;
@@ -751,13 +831,15 @@
return( 1 ); \
}
+#define SELF_TEST_OUPUT_DISCARD_LENGTH 64
+
/*
* Checkup routine
*/
int mbedtls_ctr_drbg_self_test( int verbose )
{
mbedtls_ctr_drbg_context ctx;
- unsigned char buf[16];
+ unsigned char buf[ sizeof( result_pr ) ];
mbedtls_ctr_drbg_init( &ctx );
@@ -768,16 +850,16 @@
mbedtls_printf( " CTR_DRBG (PR = TRUE) : " );
test_offset = 0;
- mbedtls_ctr_drbg_set_entropy_len( &ctx, 32 );
- mbedtls_ctr_drbg_set_nonce_len( &ctx, 0 );
+ mbedtls_ctr_drbg_set_entropy_len( &ctx, MBEDTLS_CTR_DRBG_KEYSIZE );
+ mbedtls_ctr_drbg_set_nonce_len( &ctx, MBEDTLS_CTR_DRBG_KEYSIZE / 2 );
CHK( mbedtls_ctr_drbg_seed( &ctx,
ctr_drbg_self_test_entropy,
(void *) entropy_source_pr,
- nonce_pers_pr, 16 ) );
+ pers_pr, MBEDTLS_CTR_DRBG_KEYSIZE ) );
mbedtls_ctr_drbg_set_prediction_resistance( &ctx, MBEDTLS_CTR_DRBG_PR_ON );
- CHK( mbedtls_ctr_drbg_random( &ctx, buf, MBEDTLS_CTR_DRBG_BLOCKSIZE ) );
- CHK( mbedtls_ctr_drbg_random( &ctx, buf, MBEDTLS_CTR_DRBG_BLOCKSIZE ) );
- CHK( memcmp( buf, result_pr, MBEDTLS_CTR_DRBG_BLOCKSIZE ) );
+ CHK( mbedtls_ctr_drbg_random( &ctx, buf, SELF_TEST_OUPUT_DISCARD_LENGTH ) );
+ CHK( mbedtls_ctr_drbg_random( &ctx, buf, sizeof( result_pr ) ) );
+ CHK( memcmp( buf, result_pr, sizeof( result_pr ) ) );
mbedtls_ctr_drbg_free( &ctx );
@@ -793,16 +875,16 @@
mbedtls_ctr_drbg_init( &ctx );
test_offset = 0;
- mbedtls_ctr_drbg_set_entropy_len( &ctx, 32 );
- mbedtls_ctr_drbg_set_nonce_len( &ctx, 0 );
+ mbedtls_ctr_drbg_set_entropy_len( &ctx, MBEDTLS_CTR_DRBG_KEYSIZE);
+ mbedtls_ctr_drbg_set_nonce_len( &ctx, MBEDTLS_CTR_DRBG_KEYSIZE / 2 );
CHK( mbedtls_ctr_drbg_seed( &ctx,
ctr_drbg_self_test_entropy,
(void *) entropy_source_nopr,
- nonce_pers_nopr, 16 ) );
- CHK( mbedtls_ctr_drbg_random( &ctx, buf, 16 ) );
+ pers_nopr, MBEDTLS_CTR_DRBG_KEYSIZE ) );
CHK( mbedtls_ctr_drbg_reseed( &ctx, NULL, 0 ) );
- CHK( mbedtls_ctr_drbg_random( &ctx, buf, 16 ) );
- CHK( memcmp( buf, result_nopr, 16 ) );
+ CHK( mbedtls_ctr_drbg_random( &ctx, buf, SELF_TEST_OUPUT_DISCARD_LENGTH ) );
+ CHK( mbedtls_ctr_drbg_random( &ctx, buf, sizeof( result_nopr ) ) );
+ CHK( memcmp( buf, result_nopr, sizeof( result_nopr ) ) );
mbedtls_ctr_drbg_free( &ctx );
