CODEWITHSUNDEEP
cryptographyerlangsha256
Zhani Baramidze
Zhani Baramidze

Reputation: 1497

how to get sha256 hashed string in erlang?

I'm trying to encrypt string via sha256 in erlang, but I could not manage to get string back. crypto:hash(sha256, somestring) gives some binary, how can I get string?

Upvotes: 3

Views: 5180

Answers (2)

user4651282
user4651282

Reputation:

The binary has to be decoded to an integer, and then printed in hexadecimal form:

1> io_lib:format("~64.16.0b", [binary:decode_unsigned(crypto:hash(sha256,
 "somenewstring"))]).
"abf8a5e4f99c89cabb25b4bfde8a1db5478da09bcbf4f1d9cdf90b7b5321e43c"

binary:decode_unsigned/1 decodes the whole binary as one large big-endian unsigned integer. An alternative would be to pattern match the binary into an integer:

2> <<Integer:256>> = crypto:hash(sha256, "somenewstring").
<<171,248,165,228,249,156,137,202,187,37,180,191,222,138,
  29,181,71,141,160,155,203,244,241,217,205,249,11,123,83,
  ...>>
3> Integer.
77784820141105809005227607825327585337759244421257967593474620236757179950140
4> io_lib:format("~64.16.0b", [Integer]).
"abf8a5e4f99c89cabb25b4bfde8a1db5478da09bcbf4f1d9cdf90b7b5321e43c"

(Note that <<Integer:256>> is equivalent to <<Integer:256/big-unsigned-integer>> since those are the default flags).

Upvotes: 11

Hynek -Pichi- Vychodil
Hynek -Pichi- Vychodil

Reputation: 26121

Alternative way how to get sha256 hashed string in Erlang:

[ element(C+1, {$0,$1,$2,$3,$4,$5,$6,$7,$8,$9,$A,$B,$C,$D,$E,$F}) || <<C:4>> <= crypto:hash(sha256,"somenewstring")]

Upvotes: 3

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