An analysis system comprising cryptanalysis means including: data capture means for relaying first data that is encrypted by a specific encryption scheme and communicated between an analysis target apparatus and a communication network , and capturing the first data; timing determining means for analyzing the first data captured by the data capture means , and determining a timing at which an encryption key that enables to decrypt the first data by the specific encryption scheme exists in the analysis target apparatus , in accordance with an analysis result and a key data acquisition policy ; memory acquisition means for acquiring second data stored in the analysis target apparatus at the timing determined by the timing determining means ; key candidate extraction means for extracting, from the second data one or more candidates of key data that include the encryption key based on data indicating a feature of the key data; and decryption means for extracting, from the extracted candidates of key data, correct key data that enables to correctly decrypt the encrypted first data, based on a result of decrypting the first data by use of the extracted candidates of key data, wherein the feature of the key data includes a type of the encryption scheme and a key candidate determination criterion, wherein the key candidate extraction means extracts, from the second data, one or more of the candidates of key data, based on key candidate determination information including the encryption scheme, and a key candidate determination criterion including information that enables to extract the candidate of key data from the second data based on the data indicating the feature of the key data used in the encryption scheme. data capture means for relaying first data that is encrypted by a specific encryption scheme and communicated between an analysis target apparatus and a communication network , and capturing the first data; timing determining means for analyzing the first data captured by the data capture means , and determining a timing at which an encryption key that enables to decrypt the first data by the specific encryption scheme exists in the analysis target apparatus , in accordance with an analysis result and a key data acquisition policy ; memory acquisition means for acquiring second data stored in the analysis target apparatus at the timing determined by the timing determining means ; key candidate extraction means for extracting, from the second data one or more candidates of key data that include the encryption key based on data indicating a feature of the key data; and decryption means for extracting, from the extracted candidates of key data, correct key data that enables to correctly decrypt the encrypted first data, based on a result of decrypting the first data by use of the extracted candidates of key data, wherein the feature of the key data includes a type of the encryption scheme and a key candidate determination criterion, wherein the key candidate extraction means extracts, from the second data, one or more of the candidates of key data, based on key candidate determination information including the encryption scheme, and a key candidate determination criterion including information that enables to extract the candidate of key data from the second data based on the data indicating the feature of the key data used in the encryption scheme. <EOS>