src/src/pdkim/pdkim-rsa.c

   1 #include "pdkim-rsa.h"
   2 #include <stdlib.h>
   3 #include <string.h>
   4 #include "polarssl/private-x509parse_c.h"
   5
   6 /* PDKIM code (not copied from polarssl) */
   7 /*
   8  * Parse a public RSA key
   9
  10 OpenSSL RSA public key ASN1 container
  11   0:d=0  hl=3 l= 159 cons: SEQUENCE
  12   3:d=1  hl=2 l=  13 cons: SEQUENCE
  13   5:d=2  hl=2 l=   9 prim: OBJECT:rsaEncryption
  14  16:d=2  hl=2 l=   0 prim: NULL
  15  18:d=1  hl=3 l= 141 prim: BIT STRING:RSAPublicKey (below)
  16
  17 RSAPublicKey ASN1 container
  18   0:d=0  hl=3 l= 137 cons: SEQUENCE
  19   3:d=1  hl=3 l= 129 prim: INTEGER:Public modulus
  20 135:d=1  hl=2 l=   3 prim: INTEGER:Public exponent
  21 */
  22
  23 int rsa_parse_public_key( rsa_context *rsa, unsigned char *buf, int buflen )
  24 {
  25     unsigned char *p, *end;
  26     int ret, len;
  27
  28     p = buf;
  29     end = buf+buflen;
  30
  31     if( ( ret = asn1_get_tag( &p, end, &len,
  32             ASN1_CONSTRUCTED | ASN1_SEQUENCE ) ) != 0 ) {
  33         return( POLARSSL_ERR_X509_KEY_INVALID_FORMAT | ret );
  34     }
  35
  36     if( ( ret = asn1_get_tag( &p, end, &len,
  37             ASN1_CONSTRUCTED | ASN1_SEQUENCE ) ) == 0 ) {
  38         /* Skip over embedded rsaEncryption Object */
  39         p+=len;
  40
  41         /* The RSAPublicKey ASN1 container is wrapped in a BIT STRING */
  42         if( ( ret = asn1_get_tag( &p, end, &len,
  43                 ASN1_BIT_STRING ) ) != 0 ) {
  44             return( POLARSSL_ERR_X509_KEY_INVALID_FORMAT | ret );
  45         }
  46
  47         /* Limit range to that BIT STRING */
  48         end = p + len;
  49         p++;
  50
  51         if( ( ret = asn1_get_tag( &p, end, &len,
  52                 ASN1_CONSTRUCTED | ASN1_SEQUENCE ) ) != 0 ) {
  53             return( POLARSSL_ERR_X509_KEY_INVALID_FORMAT | ret );
  54         }
  55     }
  56
  57     if ( ( ( ret = asn1_get_mpi( &p, end, &(rsa->N)  ) ) == 0 ) &&
  58          ( ( ret = asn1_get_mpi( &p, end, &(rsa->E)  ) ) == 0 ) ) {
  59         rsa->len = mpi_size( &rsa->N );
  60         return 0;
  61     }
  62
  63     return( POLARSSL_ERR_X509_KEY_INVALID_FORMAT | ret );
  64 }
  65
  66 /*
  67  * Parse a private RSA key
  68  */
  69 int rsa_parse_key( rsa_context *rsa, unsigned char *buf, int buflen,
  70                                      unsigned char *pwd, int pwdlen )
  71 {
  72     int ret, len, enc;
  73     unsigned char *s1, *s2;
  74     unsigned char *p, *end;
  75
  76     s1 = (unsigned char *) strstr( (char *) buf,
  77         "-----BEGIN RSA PRIVATE KEY-----" );
  78
  79     if( s1 != NULL )
  80     {
  81         s2 = (unsigned char *) strstr( (char *) buf,
  82             "-----END RSA PRIVATE KEY-----" );
  83
  84         if( s2 == NULL || s2 <= s1 )
  85             return( POLARSSL_ERR_X509_KEY_INVALID_PEM );
  86
  87         s1 += 31;
  88         if( *s1 == '\r' ) s1++;
  89         if( *s1 == '\n' ) s1++;
  90             else return( POLARSSL_ERR_X509_KEY_INVALID_PEM );
  91
  92         enc = 0;
  93
  94         if( memcmp( s1, "Proc-Type: 4,ENCRYPTED", 22 ) == 0 )
  95         {
  96             return( POLARSSL_ERR_X509_FEATURE_UNAVAILABLE );
  97         }
  98
  99         len = 0;
 100         {
 101         extern unsigned char * string_copyn(const unsigned char *, int);
 102         extern int b64decode(unsigned char *, unsigned char **);
 103 #define POLARSSL_ERR_BASE64_INVALID_CHARACTER              0x0012
 104
 105         s1 = string_copyn(s1, s2-s1); /* need nul-terminated string */
 106         if ((len = b64decode(s1, &buf)) < 0)
 107             return POLARSSL_ERR_BASE64_INVALID_CHARACTER
 108                 | POLARSSL_ERR_X509_KEY_INVALID_PEM;
 109         }
 110
 111         buflen = len;
 112
 113         if( enc != 0 )
 114         {
 115             return( POLARSSL_ERR_X509_FEATURE_UNAVAILABLE );
 116         }
 117     }
 118
 119     memset( rsa, 0, sizeof( rsa_context ) );
 120
 121     p = buf;
 122     end = buf + buflen;
 123
 124     /*
 125      *  RSAPrivateKey ::= SEQUENCE {
 126      *      version           Version,
 127      *      modulus           INTEGER,  -- n
 128      *      publicExponent    INTEGER,  -- e
 129      *      privateExponent   INTEGER,  -- d
 130      *      prime1            INTEGER,  -- p
 131      *      prime2            INTEGER,  -- q
 132      *      exponent1         INTEGER,  -- d mod (p-1)
 133      *      exponent2         INTEGER,  -- d mod (q-1)
 134      *      coefficient       INTEGER,  -- (inverse of q) mod p
 135      *      otherPrimeInfos   OtherPrimeInfos OPTIONAL
 136      *  }
 137      */
 138     if( ( ret = asn1_get_tag( &p, end, &len,
 139             ASN1_CONSTRUCTED | ASN1_SEQUENCE ) ) != 0 )
 140     {
 141         rsa_free( rsa );
 142         return( POLARSSL_ERR_X509_KEY_INVALID_FORMAT | ret );
 143     }
 144
 145     end = p + len;
 146
 147     if( ( ret = asn1_get_int( &p, end, &rsa->ver ) ) != 0 )
 148     {
 149         rsa_free( rsa );
 150         return( POLARSSL_ERR_X509_KEY_INVALID_FORMAT | ret );
 151     }
 152
 153     if( rsa->ver != 0 )
 154     {
 155         rsa_free( rsa );
 156         return( ret | POLARSSL_ERR_X509_KEY_INVALID_VERSION );
 157     }
 158
 159     if( ( ret = asn1_get_mpi( &p, end, &rsa->N  ) ) != 0 ||
 160         ( ret = asn1_get_mpi( &p, end, &rsa->E  ) ) != 0 ||
 161         ( ret = asn1_get_mpi( &p, end, &rsa->D  ) ) != 0 ||
 162         ( ret = asn1_get_mpi( &p, end, &rsa->P  ) ) != 0 ||
 163         ( ret = asn1_get_mpi( &p, end, &rsa->Q  ) ) != 0 ||
 164         ( ret = asn1_get_mpi( &p, end, &rsa->DP ) ) != 0 ||
 165         ( ret = asn1_get_mpi( &p, end, &rsa->DQ ) ) != 0 ||
 166         ( ret = asn1_get_mpi( &p, end, &rsa->QP ) ) != 0 )
 167     {
 168         rsa_free( rsa );
 169         return( ret | POLARSSL_ERR_X509_KEY_INVALID_FORMAT );
 170     }
 171
 172     rsa->len = mpi_size( &rsa->N );
 173
 174     if( p != end )
 175     {
 176         rsa_free( rsa );
 177         return( POLARSSL_ERR_X509_KEY_INVALID_FORMAT |
 178                 POLARSSL_ERR_ASN1_LENGTH_MISMATCH );
 179     }
 180
 181     if( ( ret = rsa_check_privkey( rsa ) ) != 0 )
 182     {
 183         rsa_free( rsa );
 184         return( ret );
 185     }
 186
 187     return( 0 );
 188 }