Review Article
A Survey on Breaking Technique of Text-Based CAPTCHA
Table 4
Comparisons of typical methods based on nonsegmentation for breaking adherent CAPTCHA.
| Example | Source | Success rate | Reference | Breaking method | Year |
| | EZ-Gimpy Gimpy | 92% | [20] | Shape context matching algorithm | 2003 | 33% |
| | EZ-Gimpy | 99% | [57] | Correlation algorithm | 2004 |
| | Program generation | 55% | [62] | RNN | 2011 |
| | Program generation | 54.9% | [63] | 2D LSTM-RNN | 2013 |
| | reCAPTCHA | 99.8% | [30] | DCNN | 2013 |
| | reCAPTCHA | 31.75% | [64] | HMM | 2015 |
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Note. RNN: recurrent neural network, 2D LSTM: 2-dimensional long short-term memory, DCNN: spatial displacement of the neutral network, HMM: Hidden Markov model.
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