StackOverflow2013

Note that there are some explanatory texts on larger screens.

plurals

PODifferent signatures when using C routines and openssl dgst, rsautl commands
primarykey
Id
9380856
data
AcceptedAnswerId
0
AnswerCount
2
ClosedDate
CommentCount
0
CommunityOwnedDate
CreationDate
2012-02-21T16:08:00.350
FavoriteCount
0
LastActivityDate
2017-03-18T16:12:11.320
LastEditDate
2017-03-18T16:12:11.320
LastEditorUserId
608639
OwnerUserId
1223747
ParentId
0
PostTypeId
1
Score
4
ViewCount
5379
LastEditorDisplayName
text
Body
I am using following statement to create a RSA public and private key. openssl genrsa -out ksign_private.pem 1024 openssl rsa -in ksign_private.pem -pubout > ksign_public.pem Then I have program that uses, PEM_read_RSAPrivateKey, EVP_PKEY_assign_RSA, EVP_SignInit, EVP_SignUpdate, EVP_SignFinal functions from openssl libcrypto to generate signature file. I also have routine that verifies that signature can be verified using PEM_read_RSA_PUBKEY, EVP_PKEY_assign_RSA, EVP_VerifyInit, EVP_VerifyUpdate, EVP_VerifyFinal. Source code for these routines is attached below. When using these functions I can create SHA1 signature, encrypt it with private key, and decrypt it using public key. However I tried to use the same data file, same private, public key using the openssl rsautl and the signature that is getting created by openssl rsautl is vastly different. <pre><code>openssl dgst -sha1 -binary < myData > testfile.sha1 openssl rsautl -sign -in testfile.sha1 -inkey ksign_private.pem -keyform PEM -out testfile.sig </code></pre> Can any one tell me what options I am using wrong when using openssl rsautl or dgst command? <pre><code>#include <stdio.h> #include <unistd.h> #include <stdlib.h> #include <ctype.h> #include <unistd.h> #include <string.h> #include <openssl/sha.h> #include <errno.h> #include <getopt.h> #include <sys/types.h> #include <sys/stat.h> #include <openssl/evp.h> #include <openssl/pem.h> #include <openssl/rsa.h> int ksignEvpSign(FILE * private_key, FILE * inFileFP, FILE * outFileFP); int ksignEvpVerify(FILE * public_key, FILE * dataFileFP, FILE * signFileFP); int ksignEvpSign(FILE * privateKeyFP, FILE * inFileFP, FILE * outFileFP) { RSA *rsa_pkey = NULL; EVP_PKEY *pkey = EVP_PKEY_new(); EVP_MD_CTX ctx; unsigned char buffer[4096]; size_t len; unsigned char *sig; unsigned int siglen; if (!PEM_read_RSAPrivateKey(privateKeyFP, &rsa_pkey, NULL, NULL)) { fprintf(stderr, "Error loading RSA Private Key File.\n"); return 2; } if (!EVP_PKEY_assign_RSA(pkey, rsa_pkey)) { fprintf(stderr, "EVP_PKEY_assign_RSA: failed.\n"); return 3; } EVP_MD_CTX_init(&ctx); if (!EVP_SignInit(&ctx, EVP_sha1())) { fprintf(stderr, "EVP_SignInit: failed.\n"); EVP_PKEY_free(pkey); return 3; } while ((len = fread(buffer, 1, sizeof buffer, inFileFP)) > 0) { if (!EVP_SignUpdate(&ctx, buffer, len)) { fprintf(stderr, "EVP_SignUpdate: failed.\n"); EVP_PKEY_free(pkey); return 3; } } if (ferror(inFileFP)) { perror("input file"); EVP_PKEY_free(pkey); return 4; } sig = malloc(EVP_PKEY_size(pkey)); if (!EVP_SignFinal(&ctx, sig, &siglen, pkey)) { fprintf(stderr, "EVP_SignFinal: failed.\n"); free(sig); EVP_PKEY_free(pkey); return 3; } fwrite(sig, siglen, 1, outFileFP); free(sig); EVP_PKEY_free(pkey); return 0; } int ksignEvpVerify(FILE * publicKeyFP, FILE * dataFileFP, FILE * sigFileFP) { RSA *rsa_pkey = NULL; EVP_PKEY *pkey; EVP_MD_CTX ctx; unsigned char buffer[4096]; size_t len; unsigned char *sig; unsigned int siglen; struct stat stat_buf; if (!PEM_read_RSA_PUBKEY(publicKeyFP, &rsa_pkey, NULL, NULL)) { fprintf(stderr, "Error loading RSA public Key File.\n"); return 2; } pkey = EVP_PKEY_new(); if (!EVP_PKEY_assign_RSA(pkey, rsa_pkey)) { fprintf(stderr, "EVP_PKEY_assign_RSA: failed.\n"); return 3; } /* Read the signature */ if (fstat(fileno(sigFileFP), &stat_buf) == -1) { fprintf(stderr, "Unable to read signature \n"); return 4; } siglen = stat_buf.st_size; sig = (unsigned char *)malloc(siglen); if (sig == NULL) { fprintf(stderr, "Unable to allocated %d bytes for signature\n", siglen); return 5; } if ((fread(sig, 1, siglen, sigFileFP)) != siglen) { fprintf(stderr, "Unable to read %d bytes for signature\n", siglen); return 6; } /* printf("Signature:"); for (i = 0; i < siglen; i++) { fprintf(stdout, "%02x", sig[i]); if (i % 16 == 15) fprintf(stdout, "\n"); } fprintf(stdout, "\n"); */ EVP_MD_CTX_init(&ctx); if (!EVP_VerifyInit(&ctx, EVP_sha1())) { fprintf(stderr, "EVP_SignInit: failed.\n"); EVP_PKEY_free(pkey); return 7; } while ((len = fread(buffer, 1, sizeof buffer, dataFileFP)) > 0) { if (!EVP_VerifyUpdate(&ctx, buffer, len)) { fprintf(stderr, "EVP_SignUpdate: failed.\n"); EVP_PKEY_free(pkey); return 8; } } if (ferror(dataFileFP)) { perror("input file"); EVP_PKEY_free(pkey); return 9; } if (!EVP_VerifyFinal(&ctx, sig, siglen, pkey)) { fprintf(stderr, "EVP_VerifyFinal: failed.\n"); free(sig); EVP_PKEY_free(pkey); return 10; } free(sig); EVP_PKEY_free(pkey); return 0; } </code></pre>
Tags
<c><openssl><rsa><signature>
Title
Different signatures when using C routines and openssl dgst, rsautl commands
singulars
PostAcceptedAnswerId
1. This table or related slice is empty.
PostParentId
1. This table or related slice is empty.
PostTypePostTypeId
1. PTQuestion
UserLastEditorUserId
1. USjww
UserOwnerUserId
1. USSubodh Nijsure
plurals
PostLinksPostIdRelatedPostId
1. This table or related slice is empty.
PostLinksRelatedPostIdPostId
1. PL
 singulars
 LinkTypeLinkTypeId
 LTLinked
2. PL
 singulars
 LinkTypeLinkTypeId
 LTLinked
PostsAcceptedAnswerId
1. This table or related slice is empty.
PostsParentIdCreationDate
1. PO
 singulars
 PostTypePostTypeId
 PTAnswer
2. PO
 singulars
 PostTypePostTypeId
 PTAnswer
VotesPostIdCreationDate
1. This table or related slice is empty.
CommentsPostId
1. This table or related slice is empty.

Querying!

Guidance

A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.