In the actual event, however, no early NSA cracker had to go at it. Wilkinson, as the recipient of the letter, provided an ostensibly accurate decoded copy to Jefferson, which formed the basis of his federal charges.
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It’s a fascinating time in America: Aaron Burr has returned to the limelight as an antagonist in the hottest ticket on Broadway, and a case in which he was involved became an issue of contention in the most fraught battle over the future of strong encryption. Having explained the encryption used in the letter at issue, let’s look at the actual trial.
In a brief filed March 10 by the Department of Justice in the ongoing battle to determine whether Apple has to create a custom operating system to allow the FBI to attempt decrypting a phone owned by one of the terrorists in the San Bernardino tragedy, this remarkable statement appeared:
Contrary to Apple’s argument, the Order does not require it to “provide decryption services” to the government. But that would not be novel, either. Indeed, no less an authority than Chief Justice Marshall held that Aaron Burr’s clerk could be forced to decipher a coded letter of Burr’s, provided that doing so would not incriminate the clerk. See United States v. Burr, 25 F. Cas. 38, 39-40 (C.C. Va. 1807).
Apple’s rejoinder appeared as a footnote in its filing six days later (the term “cipher” here refers to the encoded message):
The government contends that Chief Justice Marshall once ordered a third party to “provide decryption services” to the government. Opp. 20 (citing United States v. Burr, 25 F. Cas. 38 (C.C.D. Va. 1807) (No. 14692E)). He did nothing of the sort, and the All Writs Act was not even at issue in Burr. In that case, Aaron Burr’s secretary declined to state whether he “understood” the contents of a certain letter written in cipher, on the ground that he might incriminate himself. 25 F. Cas. at 39. The Court held that the clerk’s answer as to whether he understood the cipher could not incriminate him, and the Court thus held that “the witness may answer the question now propounded”—i.e., whether he understood the letter. Id. at 40. The Court did not require the clerk to decipher the letter.
The case at hand was a trial over whether Burr and some accomplices were attempting to raise an army to wage war either within or without the bounds of the United States. The charges were treason and “high misdemeanor.” Jefferson in pursuing the charges and a grand jury in indicting Burr covered both treason defined narrowly in the Constitution (waging war against the United States) and the misdemeanor charge, which would cover violation of a neutrality treaty to engage in military operations against another nation (here, Spain) if the United States wasn’t itself in a state of war.
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