RSA Signature Generator (SHA256withRSA) — Produce an RSA signature without leaving the browser. Paste a private key and a message, and you get the Base64 signature back — the same value you would get from `openssl dgst -sha256 -sign`.
Your private key is processed in this browser tab and never sent anywhere — there is no server. Nothing is stored, so reloading the page clears it.
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What is RSA Signature Generator (SHA256withRSA)?
Produce an RSA signature without leaving the browser. Paste a private key and a message, and you get the Base64 signature back — the same value you would get from `openssl dgst -sha256 -sign`.
This is the scheme Indonesian payment APIs use for the X-SIGNATURE header: SHA256withRSA, also called RSASSA-PKCS1-v1_5. It is not the same as RSASSA-PSS, and a signature made with one is rejected by a verifier expecting the other.
How to use it
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Paste your private key
PKCS#8 (BEGIN PRIVATE KEY) and PKCS#1 (BEGIN RSA PRIVATE KEY) both work.
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Paste the string to sign
The exact text, with no trailing newline.
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Copy the signature
Base64, ready for an X-SIGNATURE header.
Frequently asked questions
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Last reviewed: 2026-10-22