| .TH DSA 3 | |
| .SH NAME | |
| dsagen, dsasign, dsaverify, dsapuballoc, dsapubfree, dsaprivalloc, dsaprivfree, dsasigalloc, dsasigfree, dsaprivtopub - digital signature algorithm | |
| .SH SYNOPSIS | |
| .B #include <u.h> | |
| .br | |
| .B #include <libc.h> | |
| .br | |
| .B #include <mp.h> | |
| .br | |
| .B #include <libsec.h> | |
| .PP | |
| .B | |
| DSApriv* dsagen(DSApub *opub) | |
| .PP | |
| .B | |
| DSAsig* dsasign(DSApriv *k, mpint *m) | |
| .PP | |
| .B | |
| int dsaverify(DSApub *k, DSAsig *sig, mpint *m) | |
| .PP | |
| .B | |
| DSApub* dsapuballoc(void) | |
| .PP | |
| .B | |
| void dsapubfree(DSApub*) | |
| .PP | |
| .B | |
| DSApriv* dsaprivalloc(void) | |
| .PP | |
| .B | |
| void dsaprivfree(DSApriv*) | |
| .PP | |
| .B | |
| DSAsig* dsasigalloc(void) | |
| .PP | |
| .B | |
| void dsasigfree(DSAsig*) | |
| .PP | |
| .B | |
| DSApub* dsaprivtopub(DSApriv*) | |
| .SH DESCRIPTION | |
| .PP | |
| DSA is the NIST approved digital signature algorithm. The owner of a key publishes | |
| the public part of the key: | |
| .EX | |
| struct DSApub | |
| { | |
| mpint *p; // modulus | |
| mpint *q; // group order, q divides p-1 | |
| mpint *alpha; // group generator | |
| mpint *key; // alpha**secret mod p | |
| }; | |
| .EE | |
| This part can be used for verifying signatures (with | |
| .IR dsaverify ) | |
| created by the owner. | |
| The owner signs (with | |
| .IR dsasign ) | |
| using his private key: | |
| .EX | |
| struct DSApriv | |
| { | |
| DSApub pub; | |
| mpint *secret; // (decryption key) | |
| }; | |
| .EE | |
| .PP | |
| Keys are generated using | |
| .IR dsagen . | |
| If | |
| .IR dsagen 's | |
| argument | |
| .I opub | |
| is | |
| .BR nil , | |
| a key is created using a new | |
| .B p | |
| and | |
| .B q | |
| generated by | |
| .IR DSAprimes | |
| (see | |
| .IR prime (3)). | |
| Otherwise, | |
| .B p | |
| and | |
| .B q | |
| are copied from the old key. | |
| .PP | |
| .I Dsaprivtopub | |
| returns a newly allocated copy of the public key | |
| corresponding to the private key. | |
| .PP | |
| The routines | |
| .IR dsapuballoc , | |
| .IR dsapubfree , | |
| .IR dsaprivalloc , | |
| and | |
| .I dsaprivfree | |
| are provided to manage key storage. | |
| .PP | |
| .I Dsasign | |
| signs message | |
| .I m | |
| using a private key | |
| .I k | |
| yielding a | |
| .EX | |
| struct DSAsig | |
| { | |
| mpint *r, *s; | |
| }; | |
| .EE | |
| .I Dsaverify | |
| returns 0 if the signature is valid and \-1 if not. | |
| .PP | |
| The routines | |
| .I dsasigalloc | |
| and | |
| .I dsasigfree | |
| are provided to manage signature storage. | |
| .SH SOURCE | |
| .B \*9/src/libsec | |
| .SH SEE ALSO | |
| .IR mp (3), | |
| .IR aes (3), | |
| .IR blowfish (3), | |
| .IR des (3), | |
| .IR rc4 (3), | |
| .IR rsa (3), | |
| .IR sechash (3), | |
| .IR prime (3), | |
| .IR rand (3) |