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Fix RSA signatures #82

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merged 7 commits into from
May 17, 2017
Merged

Fix RSA signatures #82

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ed82e3d
Fix RSA signatures.
May 13, 2017
836e42e
Fix reliance on uninitialized out_length for RSA signing.
May 13, 2017
b69f67e
Add stricter error checking for RSA signing.
May 13, 2017
0aa1c26
Remove (hopefully) legacy code from signature check.
May 13, 2017
77bdd7d
Add out_length as an explicit parameter to pgp_rsa_private_encrypt.
May 16, 2017
e458fdc
Zero the buffer in pgp_rsa_public_decrypt so we're not using uninitia…
May 17, 2017
9e56883
Undo commit 'Remove (hopefully) legacy code from signature check'.
May 17, 2017
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2 changes: 1 addition & 1 deletion src/lib/crypto.h
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Original file line number Diff line number Diff line change
Expand Up @@ -147,7 +147,7 @@ int pgp_rsa_decrypt_pkcs1(uint8_t* out, size_t out_len,
int pgp_rsa_public_decrypt(uint8_t *, const uint8_t *, size_t,
const pgp_rsa_pubkey_t *);

int pgp_rsa_private_encrypt(uint8_t *, const uint8_t *, size_t,
int pgp_rsa_private_encrypt(uint8_t *, size_t, const uint8_t *, size_t,
const pgp_rsa_seckey_t *, const pgp_rsa_pubkey_t *);

/*
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17 changes: 13 additions & 4 deletions src/lib/rsa.c
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Expand Up @@ -80,6 +80,8 @@
#include "readerwriter.h"
#include "rnpdefs.h"

#include <string.h>

/**
\ingroup Core_Crypto
\brief Recovers message digest from the signature
Expand Down Expand Up @@ -112,6 +114,7 @@ pgp_rsa_public_decrypt(uint8_t *out,
if(n_bytes < out_bytes)
return 0;

memset(out, 0, n_bytes);
botan_mp_to_bin(output, out + (n_bytes - out_bytes));

return n_bytes;
Expand Down Expand Up @@ -183,6 +186,7 @@ pgp_rsa_encrypt_pkcs1(uint8_t *out,
*/
int
pgp_rsa_private_encrypt(uint8_t *out,
size_t out_length,
const uint8_t *in,
size_t in_length,
const pgp_rsa_seckey_t *seckey,
Expand All @@ -192,7 +196,6 @@ pgp_rsa_private_encrypt(uint8_t *out,
botan_privkey_t rsa_key;
botan_pk_op_sign_t sign_op;
botan_rng_t rng;
size_t out_length;

if(seckey->q == NULL)
{
Expand All @@ -203,7 +206,7 @@ pgp_rsa_private_encrypt(uint8_t *out,
botan_rng_init(&rng, NULL);

/* p and q are reversed from normal usage in PGP */
botan_privkey_load_rsa(&rsa_key, seckey->q->mp, seckey->p->mp, seckey->d->mp);
botan_privkey_load_rsa(&rsa_key, seckey->q->mp, seckey->p->mp, pubkey->e->mp);

if(botan_privkey_check_key(rsa_key, rng, 0) != 0)
{
Expand All @@ -219,8 +222,14 @@ pgp_rsa_private_encrypt(uint8_t *out,
return 0;
}

botan_pk_op_sign_update(sign_op, in, in_length);
botan_pk_op_sign_finish(sign_op, rng, out, &out_length);
if (botan_pk_op_sign_update(sign_op, in, in_length) != 0 ||
botan_pk_op_sign_finish(sign_op, rng, out, &out_length) != 0)
{
botan_pk_op_sign_destroy(sign_op);
botan_privkey_destroy(rsa_key);
botan_rng_destroy(rng);
return 0;
}

botan_pk_op_sign_destroy(sign_op);
botan_privkey_destroy(rsa_key);
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8 changes: 5 additions & 3 deletions src/lib/signature.c
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Expand Up @@ -216,7 +216,11 @@ rsa_sign(pgp_hash_t *hash,
return 0;
}

t = pgp_rsa_private_encrypt(sigbuf, hashbuf, keysize, secrsa, pubrsa);
t = pgp_rsa_private_encrypt(sigbuf, sizeof(sigbuf), hashbuf, keysize, secrsa, pubrsa);
if (t == 0) {
(void) fprintf(stderr, "rsa_sign: pgp_rsa_private_encrypt failed\n");
return 0;
}
bn = BN_bin2bn(sigbuf, (int)t, NULL);
pgp_write_mpi(out, bn);
BN_free(bn);
Expand Down Expand Up @@ -297,8 +301,6 @@ rsa_verify(pgp_hash_alg_t type,
return 0;
}

/* XXX: why is there a leading 0? The first byte should be 1... */
/* XXX: because the decrypt should use keysize and not sigsize? */
if (hashbuf_from_sig[0] != 0 || hashbuf_from_sig[1] != 1) {
return 0;
}
Expand Down