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CTR_DRBG: Don't use functions before they're defined

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Move the definitions of mbedtls_ctr_drbg_seed_entropy_len() and
mbedtls_ctr_drbg_seed() to after they are used. This makes the code
easier to read and to maintain.
This commit is contained in:
Gilles Peskine 2019-10-02 20:31:54 +02:00
parent 8f7921ec4b
commit 8bf5613336
1 changed files with 64 additions and 64 deletions
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128
library/ctr_drbg.c
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@ -62,70 +62,6 @@ void mbedtls_ctr_drbg_init( mbedtls_ctr_drbg_context *ctx )
#endif
}
/*
* Non-public function wrapped by mbedtls_ctr_drbg_seed(). Necessary to allow
* NIST tests to succeed (which require known length fixed entropy)
*/
/* CTR_DRBG_Instantiate with derivation function (SP 800-90A §10.2.1.3.2)
* mbedtls_ctr_drbg_seed_entropy_len(ctx, f_entropy, p_entropy,
* custom, len, entropy_len)
* implements
* CTR_DRBG_Instantiate(entropy_input, nonce, personalization_string,
* security_strength) -> initial_working_state
* with inputs
* custom[:len] = nonce || personalization_string
* where entropy_input comes from f_entropy for entropy_len bytes
* and with outputs
* ctx = initial_working_state
*/
int mbedtls_ctr_drbg_seed_entropy_len(
mbedtls_ctr_drbg_context *ctx,
int (*f_entropy)(void *, unsigned char *, size_t),
void *p_entropy,
const unsigned char *custom,
size_t len,
size_t entropy_len )
{
int ret;
unsigned char key[MBEDTLS_CTR_DRBG_KEYSIZE];
memset( key, 0, MBEDTLS_CTR_DRBG_KEYSIZE );
mbedtls_aes_init( &ctx->aes_ctx );
ctx->f_entropy = f_entropy;
ctx->p_entropy = p_entropy;
ctx->entropy_len = entropy_len;
ctx->reseed_interval = MBEDTLS_CTR_DRBG_RESEED_INTERVAL;
/*
* Initialize with an empty key
*/
if( ( ret = mbedtls_aes_setkey_enc( &ctx->aes_ctx, key,
MBEDTLS_CTR_DRBG_KEYBITS ) ) != 0 )
{
return( ret );
}
if( ( ret = mbedtls_ctr_drbg_reseed( ctx, custom, len ) ) != 0 )
{
return( ret );
}
return( 0 );
}
int mbedtls_ctr_drbg_seed( mbedtls_ctr_drbg_context *ctx,
int (*f_entropy)(void *, unsigned char *, size_t),
void *p_entropy,
const unsigned char *custom,
size_t len )
{
return( mbedtls_ctr_drbg_seed_entropy_len( ctx, f_entropy, p_entropy,
custom, len,
MBEDTLS_CTR_DRBG_ENTROPY_LEN ) );
}
void mbedtls_ctr_drbg_free( mbedtls_ctr_drbg_context *ctx )
{
if( ctx == NULL )
@ -445,6 +381,70 @@ exit:
return( ret );
}
/*
* Non-public function wrapped by mbedtls_ctr_drbg_seed(). Necessary to allow
* NIST tests to succeed (which require known length fixed entropy)
*/
/* CTR_DRBG_Instantiate with derivation function (SP 800-90A §10.2.1.3.2)
* mbedtls_ctr_drbg_seed_entropy_len(ctx, f_entropy, p_entropy,
* custom, len, entropy_len)
* implements
* CTR_DRBG_Instantiate(entropy_input, nonce, personalization_string,
* security_strength) -> initial_working_state
* with inputs
* custom[:len] = nonce || personalization_string
* where entropy_input comes from f_entropy for entropy_len bytes
* and with outputs
* ctx = initial_working_state
*/
int mbedtls_ctr_drbg_seed_entropy_len(
mbedtls_ctr_drbg_context *ctx,
int (*f_entropy)(void *, unsigned char *, size_t),
void *p_entropy,
const unsigned char *custom,
size_t len,
size_t entropy_len )
{
int ret;
unsigned char key[MBEDTLS_CTR_DRBG_KEYSIZE];
memset( key, 0, MBEDTLS_CTR_DRBG_KEYSIZE );
mbedtls_aes_init( &ctx->aes_ctx );
ctx->f_entropy = f_entropy;
ctx->p_entropy = p_entropy;
ctx->entropy_len = entropy_len;
ctx->reseed_interval = MBEDTLS_CTR_DRBG_RESEED_INTERVAL;
/*
* Initialize with an empty key
*/
if( ( ret = mbedtls_aes_setkey_enc( &ctx->aes_ctx, key,
MBEDTLS_CTR_DRBG_KEYBITS ) ) != 0 )
{
return( ret );
}
if( ( ret = mbedtls_ctr_drbg_reseed( ctx, custom, len ) ) != 0 )
{
return( ret );
}
return( 0 );
}
int mbedtls_ctr_drbg_seed( mbedtls_ctr_drbg_context *ctx,
int (*f_entropy)(void *, unsigned char *, size_t),
void *p_entropy,
const unsigned char *custom,
size_t len )
{
return( mbedtls_ctr_drbg_seed_entropy_len( ctx, f_entropy, p_entropy,
custom, len,
MBEDTLS_CTR_DRBG_ENTROPY_LEN ) );
}
/* CTR_DRBG_Generate with derivation function (SP 800-90A §10.2.1.5.2)
* mbedtls_ctr_drbg_random_with_add(ctx, output, output_len, additional, add_len)
* implements