Ok, more source diving. Bitcoin Wallet calls into bitcoinj java/com/google/bitcoin/core/Wallet.java sendCoinsOffline(...), which calls completeTx(...), which ca

Ok, more source diving. Bitcoin Wallet calls into bitcoinj java/com/google/bitcoin/core/Wallet.java sendCoinsOffline(...), which calls completeTx(...), which calls core/Transaction.java signInputs(...), which calls calculateSignature(...), which calls core/ECKey.java sign(...), which performs: ECDSASigner signer = new ECDSASigner(); ECPrivateKeyParameters privKey = new ECPrivateKeyParameters(privateKeyForSigning, ecParams); signer.init(true, privKey); BigInteger[] sigs = signer.generateSignature(input.getBytes()); return new ECDSASignature(sigs[0], sigs[1]); This _appears_ to be a correct invocation of spongycastle-formerly-bouncycastle, initializing the signer with an instance of ECPrivateKeyParametes, and NOT an instance of ParametersWithRandom, so that, on org/spongycastle/crypto/signers/ECDSASigner.java line 41, we call SecureRandom() with no arguments. I don't see spongycastle ever calling setSeed, and I don't see it ever leaking its SecureRandom instance, so unless calling setSeed on ANY SecureRandom instance is a problem, this _looks_ like a correct usage. Also, I now remember how much I hate reading Java.