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Using OpenSSL ver 1.1.0h on win 8.1 - 32 bit

Im trying to recreate this post using cmd: OpenSSL generate Bitcoin address

But on step 3:

openssl ec -in c:\keys\private.pem -outform DER|tail -c +8|head -c 32|xxd -p -c 32 > c:\keys\private.key

I got this error: ec: Unknown cipher c

Any idea what im doing going wrong?

  • Try putting c:\keys\private.pem in quotes, like "c:\keys\private.pem" – Raghav Sood Jul 26 '18 at 1:13
  • I got the samme error :( – Pedro Jose Otero Rodriguez Jul 26 '18 at 1:21
  • I don't have a windows machine on hand, but it's probably just a location issue. Try moving private.pem to the same directory you're running the command from, and using a relative path – Raghav Sood Jul 26 '18 at 1:22
  • If it is a locations issue, why steps 1&2 works ok? – Pedro Jose Otero Rodriguez Jul 26 '18 at 1:38
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I did the same exercise on my OSX system, and this is my result:

$ openssl version
OpenSSL 1.0.2j  26 Sep 2016

$ openssl ec -in privkey.pem -outform DER|tail -c +8|head -c 32|xxd -p -c 32
read EC key
writing EC key
18e14a7b6a307f426a94f8114701e7c8e774e7f9a47e2c2035db29a206321725

I assume that the PEM key is not in correct format, PEM follows some specific rules. There are several discussions also here in bitcoin.SE

My privkey.pem looks like this:

$ cat privkey.pem
-----BEGIN EC PRIVATE KEY-----
MFQCAQEEIBjhSntqMH9CapT4EUcB58jndOf5pH4sIDXbKaIGMhcloAcGBSuBBAAK
oSQDIgACUIY61kqHroov6Dwa8ahAPLU/U+SG2FEdrYoEiH5bI1I=
-----END EC PRIVATE KEY-----

This is a "test" key, note the word "Risc" in the generated bitcoin address from this key. Don't use it for any value, the funds will get lost. If you have a test key, and really it is a test key, you can share it, and we can have a look at it (and you will then never ever use it again).

  • I guess is more something about OpenSSL version. Even in the same thread i mention as source, other user comments that with 1.0.2 it is working too. Looks like it is a little bug – Pedro Jose Otero Rodriguez Jul 28 '18 at 1:18

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