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RSA-OAEP decrypt: reorganise code

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Manuel Pégourié-Gonnard 2013-11-28 15:57:52 +01:00 committed by Paul Bakker
parent a91d41e7a4
commit 3411464a64
1 changed files with 35 additions and 26 deletions
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61
library/rsa.c
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@ -591,6 +591,9 @@ int rsa_rsaes_oaep_decrypt( rsa_context *ctx,
const md_info_t *md_info; const md_info_t *md_info;
md_context_t md_ctx; md_context_t md_ctx;
/*
* Parameters sanity checks
*/
if( ctx->padding != RSA_PKCS_V21 ) if( ctx->padding != RSA_PKCS_V21 )
return( POLARSSL_ERR_RSA_BAD_INPUT_DATA ); return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
@ -599,6 +602,13 @@ int rsa_rsaes_oaep_decrypt( rsa_context *ctx,
if( ilen < 16 || ilen > sizeof( buf ) ) if( ilen < 16 || ilen > sizeof( buf ) )
return( POLARSSL_ERR_RSA_BAD_INPUT_DATA ); return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
md_info = md_info_from_type( ctx->hash_id );
if( md_info == NULL )
return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
/*
* RSA operation
*/
ret = ( mode == RSA_PUBLIC ) ret = ( mode == RSA_PUBLIC )
? rsa_public( ctx, input, buf ) ? rsa_public( ctx, input, buf )
: rsa_private( ctx, f_rng, p_rng, input, buf ); : rsa_private( ctx, f_rng, p_rng, input, buf );
@ -606,38 +616,37 @@ int rsa_rsaes_oaep_decrypt( rsa_context *ctx,
if( ret != 0 ) if( ret != 0 )
return( ret ); return( ret );
/*
* Unmask data
*/
hlen = md_get_size( md_info );
md_init_ctx( &md_ctx, md_info );
/* Generate lHash */
md( md_info, label, label_len, lhash );
/* seed: Apply seedMask to maskedSeed */
mgf_mask( buf + 1, hlen, buf + hlen + 1, ilen - hlen - 1,
&md_ctx );
/* DB: Apply dbMask to maskedDB */
mgf_mask( buf + hlen + 1, ilen - hlen - 1, buf + 1, hlen,
&md_ctx );
md_free_ctx( &md_ctx );
/*
* Check contents
*/
p = buf; p = buf;
if( *p++ != 0 ) if( *p++ != 0 )
return( POLARSSL_ERR_RSA_INVALID_PADDING ); return( POLARSSL_ERR_RSA_INVALID_PADDING );
md_info = md_info_from_type( ctx->hash_id ); p += hlen; /* Skip seed */
if( md_info == NULL )
return( POLARSSL_ERR_RSA_BAD_INPUT_DATA );
hlen = md_get_size( md_info ); /* Check lHash */
md_init_ctx( &md_ctx, md_info );
// Generate lHash
//
md( md_info, label, label_len, lhash );
// seed: Apply seedMask to maskedSeed
//
mgf_mask( buf + 1, hlen, buf + hlen + 1, ilen - hlen - 1,
&md_ctx );
// DB: Apply dbMask to maskedDB
//
mgf_mask( buf + hlen + 1, ilen - hlen - 1, buf + 1, hlen,
&md_ctx );
p += hlen;
md_free_ctx( &md_ctx );
// Check validity
//
if( memcmp( lhash, p, hlen ) != 0 ) if( memcmp( lhash, p, hlen ) != 0 )
return( POLARSSL_ERR_RSA_INVALID_PADDING ); return( POLARSSL_ERR_RSA_INVALID_PADDING );