signing alogrithm in eosjs-ecc yields different signature from that in eos!

Hi,

I'm working on signature related development and I find that signing alogrithm in eosjs-ecc yields different signature from that in eos!!!! Both tag is dawn-v4.0.0.

Reproduce steps:

Firstly let's generate a signature from eos networks.

1 ) Let's have a transaction, for example:

{"expiration":"2018-05-23T07:29:11","ref_block_num":1,"ref_block_prefix":2,"max_net_usage_words":3,"max_cpu_usage_ms":4,"delay_sec":5,"context_free_actions":[],"actions":[{"account":"eosio.token","name":"issue","authorization":[{"actor":"eosio.token","permission":"active"}],"data":"0000000000ea305580969800000000000455445400000000056973737565"}],"transaction_extensions":[],"signatures":[],"context_free_data":[]}

And we use the default private key 5KQwrPbwdL6PhXujxW37FSSQZ1JiwsST4cqQzDeyXtP79zkvFD3

2 ) I add some printing statements in private_key.cpp:


3 ) I send this transaction to v1/wallet/sign_transaction interface via rpc. Then in eos side, we know the digest of the transaction is 9d8815193d76ee236ef08e8b9fb675e6def3af8d8209d7665540ab9e17944e19 (in hex)


4 ) The sign_transaction yields result:

{"expiration":"2018-05-22T23:29:11.000+0000","refBlockNum":1,"refBlockPrefix":2,"maxNetUsageWords":3,"maxKcpuUsageMs":4,"delaySec":5,"contextFreeActions":[],"actions":[{"account":"eosio.token","name":"issue","authorization":[{"actor":"eosio.token","permission":"active"}],"data":"0000000000ea305580969800000000000455445400000000056973737565"}],"transactionExtensions":[],"signatures":["SIG_K1_K3dztmFctY8QPgD6BEnxaV4s1gxyfHPZYTqHx8gH9Hiq2MLvn8Uc4ki6w7C89GVXAQ5JFM37BERe5qJSVHAqSkD8AabtKR"],"contextFreeData":[]}

You can see the signature is :

SIG_K1_K3dztmFctY8QPgD6BEnxaV4s1gxyfHPZYTqHx8gH9Hiq2MLvn8Uc4ki6w7C89GVXAQ5JFM37BERe5qJSVHAqSkD8AabtKR

Now let's try it from eosjs-ecc. Steps:

1 ) I write some simple code. The input:

Digest: 9d8815193d76ee236ef08e8b9fb675e6def3af8d8209d7665540ab9e17944e19

private key: 5KQwrPbwdL6PhXujxW37FSSQZ1JiwsST4cqQzDeyXtP79zkvFD3


2 ) Execute the code, the signature is:

SIG_K1_KgMrn3yteiHtoUnqBjBcVhjuJRkeXAfwaYFQaCDmMC6sD7mGU5qQRaz3GHWe96Mfvq5Ei56EHBiwjh7sg6GYjBGzcRv81Y


Background:

I'm writing a java based eos library and I've finished the java version fc-library. For the same transaction the java version fc-library yields same digest with eos side, however the final signatures are different(although I use the same private key). The signature in eos code refers to secp256k1.c in bitcoin and it is too hard for me to investigate so I have to refer to the eosjs-ecc for the ecc signing algorithm however by which I found that even for same digest and same private key the eosjs-ecc yields different signatures with this eos repository!!!

Any solution or advice on this please?

Regards