Ethereum: What is the maximum size of a DER encoded ECDSA signature?

The Maximum Size of a DER Encoded ECDSA Signature: A Deep Dive into Bitcoin

As a seasoned Bitcoin enthusiast, you’re no stranger to the complexities of digital signatures in this cryptocurrency. One aspect of these signatures that has piqued your curiosity is the maximum size limit imposed by Ethereum on DER (Encrypted Data) encoded ECDSA signatures.

To answer your question directly, there isn’t a straightforward answer. However, I’ll provide an analysis based on the provided information and other relevant sources.

The Limitations

In Bitcoin, ECDSA signatures are typically 64 bytes in length for public key signatures. This is due to several factors:

• Compression: To reduce storage requirements, Bitcoin’s implementation uses a variable-length encoding (VLE) scheme that compresses the signature into a shorter form.

• Security: While longer signatures provide more security against attacks like padding oracle attacks, they also increase the computational overhead and storage requirements.

Ethereum’s Approach

When it comes to DER encoded ECDSA signatures on Ethereum, the situation is different. According to an answer on Why the Bitcoin community hates Ethereum, a seasoned contributor mentions that public key signatures can be up to 75 bytes in length.

To understand why this is possible, let’s dive into the details of the Ethereum implementation. The Ethereum blockchain uses a variant of the ECDSA algorithm with a compressed version of the public key, which allows for longer signature lengths.

The Math Behind it

To calculate the maximum size limit, we need to consider the compression factor and the encoding scheme used in Ethereum. Assuming a 64-byte public key, and using the variable-length encoding (VLE) scheme, we can estimate the compressed length of the signature as follows:

• Compressed public key: 8 bytes

• ECDSA compression factor: approximately 0.5

• Compressed signature length: 32 bytes

Adding these components together gives us a maximum compressed signature length of approximately 64 bytes.

Conclusion

While there isn’t a single, definitive answer to the question of what’s the maximum size limit for DER encoded ECDSA signatures on Ethereum, based on existing knowledge and research, it appears that public key signatures can be up to 75 bytes in length. However, this is likely an oversimplification and may not reflect the actual implementation or limitations in practice.

As with any complex cryptographic topic, the best approach is to consult with the relevant sources and experts in the field for more accurate information.