mirror of https://git.matrix.org/git/olm.git
41 lines
1.2 KiB
Plaintext
41 lines
1.2 KiB
Plaintext
See http://code.google.com/p/curve25519-donna/ for details.
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BUILDING:
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If you run `make`, two .a archives will be built, similar to djb's curve25519
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code. Alternatively, read on:
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The C implementation is contained within curve25519-donna.c. It has no external
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dependancies and is BSD licenced. You can copy/include/link it directly in with
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your program. Recommended C flags: -O2
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The x86-64 bit implementation is contained within curve25519-donna-x86-64.c and
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curve25519-donna-x86-64.s. Build like this:
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% cpp curve25519-donna-x86-64.s > curve25519-donna-x86-64.s.pp
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% as -o curve25519-donna-x86-64.s.o curve25519-donna-x86-64.s.pp
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% gcc -O2 -c curve25519-donna-x86-64.c
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Then the two .o files can be linked in
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USAGE:
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The usage is exactly the same as djb's code (as described at
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http://cr.yp.to/ecdh.html) expect that the function is called curve25519_donna.
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In short,
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To generate a private key just generate 32 random bytes.
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To generate the public key, just do:
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static const uint8_t basepoint[32] = {9};
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curve25519_donna(mypublic, mysecret, basepoint);
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To generate an agreed key do:
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uint8_t shared_key[32];
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curve25519_donna(shared_key, mysecret, theirpublic);
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And hash the shared_key with a cryptographic hash function before using.
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