Bitcoin Core developer and proponent of Replace-by-Fee
On December 7, 2010, a new account named “retep” registered on BitcoinTalk. Three days later, the account’s second post replied to a Satoshi Nakamoto thread on transaction-replacement fees:
“Of course, to be specific, the inputs and outputs can’t match exactly if the second transaction has a transaction fee.”
Two days later, Satoshi posted his last public message and went silent.
Years later the account’s username was changed to Peter Todd. Bitcoin Core developer Gregory Maxwell later noted on Hacker News that “it took me nearly a decade to realize retep was peter backwards.”
In October 2024, the HBO documentary “Money Electric: The Bitcoin Mystery” named Todd as a candidate for Satoshi’s true identity, pointing to the December 2010 reply as evidence. On the day of broadcast Todd told CoinDesk directly, “Of course, I’m not Satoshi,” calling filmmaker Cullen Hoback “grasping at straws.” In the film itself, asked on camera whether he was Satoshi, Todd answered sarcastically, “It’s ludicrous. But I’ll say, yeah, of course I’m Satoshi.” He treats the documentary as irresponsible.
Peter Todd is a Canadian cryptographer, applied-cryptography consultant, and Bitcoin Core developer. Before Bitcoin, he held a fine-arts degree and worked in analog-electronics design for a geophysics startup. His major Bitcoin contributions include BIP 65 OP_CHECKLOCKTIMEVERIFY (2014), co-authorship of BIP 125 Replace-by-Fee (2015), and OpenTimestamps (2016).
From April 2012, Todd’s Bitcoin Core work concentrated on the adversarial edge of the protocol — transaction policy, transaction replacement, network resilience: the parts where the requirement is set by an attacker rather than a user. By commit count he became the repository’s 11th most prolific contributor.
Todd proposed BIP 65, introducing a new opcode that allows transaction outputs to remain unspendable until a specified future time. Deployed as a soft fork, it became a building block for payment channels and the Lightning Network.
Todd is best known for championing Replace-by-Fee (RBF), which allows unconfirmed transactions to be replaced by new versions with higher fees. The concept was formalized in BIP 125, co-authored by David A. Harding and Peter Todd. The BIP’s rationale explicitly traces the concept back to Satoshi Nakamoto’s original transaction replacement mechanism.
Todd created OpenTimestamps, an open-source project that uses the Bitcoin blockchain to create tamper-proof timestamps, allowing anyone to prove that a document existed at a particular point in time. The project generalizes the timestamping function that Satoshi built into Bitcoin’s core design.
Todd was one of six participants in the Zcash trusted setup ceremony. He conducted his computation while driving across British Columbia, shielded his laptop in a Faraday cage, and destroyed the hardware with a propane torch. Despite participating, he was deeply critical of the process, stating that collusion among participants was unprovable and the unaudited deterministic builds made the ceremony “crypto hocus pocus.”
Todd contributed to the design of stealth addresses (BIP 63, unimplemented) for enhanced privacy.
He joined Coinkite in an advisory role in May 2014.
16 entries
Defines OP_CHECKLOCKTIMEVERIFY, a soft-fork opcode that makes a transaction output unspendable until a specified block height or time, enabling escrow and time-locked contracts.
Defines the original version-bits mechanism for signaling and activating soft forks in parallel via the block nVersion field, using median-time-past thresholds and a fixed timeout.
Why Bitcoin's 2015-2017 fork wars ran as identity contests, not OSS disputes: the post-2011 authority vacuum, the economic weight on rule choices, and the three layers that bound code to currency.
Editorial reading of how the 2014 'Bitcoin Core' rebrand reshaped Bitcoin's authority vocabulary — PR #3408 internal disagreement, the 2015-2017 fork episodes, and Hearn's 2025 retrospective regret.
On February 22, 2021, Evan Hatch published Len Sassaman and Satoshi: a Cypherpunk history on Medium — the article that became the foundational case for the Sassaman = Satoshi Nakamoto hypothesis.
On April 8, 2026, the New York Times published John Carreyrou's investigation naming Adam Back as the most likely Satoshi based on stylometric analysis. Back denied the identification.
A reply that read like the continuation of Satoshi's thought — and two days later, Satoshi went silent. The evidence for HBO's Peter Todd identification, weighed.
Recurring Satoshi candidates aligned across four independent layers — profile match, stylometric attribution, direct correspondence, and development environment.
Peter Todd's first BitcoinTalk post, 41 seconds after registering as retep — offering $2 USD (not BTC, unlike others) for a Diaspora invite. His second post was a technical reply to Satoshi.
Peter Todd proposed BIP 65, introducing OP_CHECKLOCKTIMEVERIFY — an opcode locking transaction outputs until a future time. Deployed as a soft fork, enabling escrow and payment channels.
BIP 125 formalized opt-in Replace-by-Fee (RBF), tracing directly to Satoshi's December 2010 BitcoinTalk replacement mechanism — the thread where Peter Todd made his second-ever forum post.
Peter Todd announced OpenTimestamps, an open-source infrastructure using the Bitcoin blockchain to timestamp unlimited documents per transaction via Merkle tree aggregation.
Peter Todd participated in the Zcash trusted setup ceremony in October 2016 — driving across BC, shielding his laptop in a Faraday cage, and torching the hardware — then criticized the process.
HBO documentary Money Electric (Cullen Hoback) named Peter Todd as a Satoshi candidate, citing a 2010 BitcoinTalk reply about RBF and Todd's later BIP 125. Todd called the claim ludicrous.
Signaling mechanism for opt-in Replace-by-Fee (RBF) — unconfirmed transactions replaceable by higher-fee versions. Improved fee estimation but controversial for zero-confirmation security.
Satoshi Nakamoto describes a possible design for transaction replacement — a higher-fee double-spend replacing the original. Later known as Replace-by-Fee (RBF). Peter Todd replied ~1.5 hours later.