[PATCH V4 05/15] asymmetric keys: implement RSASP1
From: Lee, Chun-Yi <hidden>
Date: 2013-09-15 00:57:28
Also in:
linux-efi, linux-pm, lkml
Subsystem:
asymmetric keys, crypto api, the rest · Maintainers:
David Howells, Lukas Wunner, Ignat Korchagin, Herbert Xu, "David S. Miller", Linus Torvalds
Implement RSASP1 and fill-in the following data to public key signature structure: signature length (pkcs->k), signature octet strings (pks->S) and MPI of signature (pks->rsa.s). The naming of RSASP1 and the variables used in this function accord PKCS#1 spec but not follow kernel naming convention, it useful when look at them with spec. Reference: ftp://ftp.rsasecurity.com/pub/pkcs/pkcs-1v2/pkcs1ietffinal.txt Reference: http://www.emc.com/collateral/white-papers/h11300-pkcs-1v2-2-rsa-cryptography-standard-wp.pdf Cc: Pavel Machek <redacted> Reviewed-by: Jiri Kosina <redacted> Signed-off-by: Lee, Chun-Yi <jlee-IBi9RG/b67k@public.gmane.org> --- crypto/asymmetric_keys/rsa.c | 47 +++++++++++++++++++++++++++++++++++++++-- 1 files changed, 44 insertions(+), 3 deletions(-)
diff --git a/crypto/asymmetric_keys/rsa.c b/crypto/asymmetric_keys/rsa.c
index a092aac..0ede317 100644
--- a/crypto/asymmetric_keys/rsa.c
+++ b/crypto/asymmetric_keys/rsa.c@@ -86,6 +86,39 @@ static const struct { }; /* + * RSASP1() function [RFC3447 sec 5.2.1] + */ +static int RSASP1(const struct private_key *key, MPI m, MPI *_s) +{ + MPI s; + int ret; + + /* (1) Validate 0 <= m < n */ + if (mpi_cmp_ui(m, 0) < 0) { + kleave(" = -EBADMSG [m < 0]"); + return -EBADMSG; + } + if (mpi_cmp(m, key->rsa.n) >= 0) { + kleave(" = -EBADMSG [m >= n]"); + return -EBADMSG; + } + + s = mpi_alloc(0); + if (!s) + return -ENOMEM; + + /* (2) s = m^d mod n */ + ret = mpi_powm(s, m, key->rsa.d, key->rsa.n); + if (ret < 0) { + mpi_free(s); + return ret; + } + + *_s = s; + return 0; +} + +/* * RSAVP1() function [RFC3447 sec 5.2.2] */ static int RSAVP1(const struct public_key *key, MPI s, MPI *_m)
@@ -173,9 +206,12 @@ static int RSA_I2OSP(MPI x, size_t xLen, u8 **_X) static int RSA_OS2IP(u8 *X, size_t XLen, MPI *_x) { MPI x; + int ret; x = mpi_alloc((XLen + BYTES_PER_MPI_LIMB - 1) / BYTES_PER_MPI_LIMB); - mpi_set_buffer(x, X, XLen, 0); + ret = mpi_set_buffer(x, X, XLen, 0); + if (ret < 0) + return ret; *_x = x; return 0;
@@ -460,8 +496,13 @@ static struct public_key_signature *RSA_generate_signature( if (ret < 0) goto error_v1_5_encode; - /* TODO 3): s = RSASP1 (K, m) */ - s = m; + /* 3): s = RSASP1 (K, m) */ + RSASP1(key, m, &s); + + pks->rsa.s = s; + pks->nr_mpi = 1; + pks->k = mpi_get_nbits(s); + pks->k = (pks->k + 7) / 8; /* 4): S = I2OSP (s, k) */ _RSA_I2OSP(s, &X_size, &pks->S);
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1.6.0.2